International Investment Protection Mechanisms and Dispute Resolution

After decades of surging foreign direct investment globally, often encouraged by governments seeking to incentivise the inflow of foreign capital to their economies, we are at a turning point. Recent years have seen many states seeking to reassert control over their natural resources, put in place measures to protect the environment or combat climate change, or altering previously favourable investment regimes to reduce their budgetary commitments. These state measures often conflict with foreign investors' legitimate expectations, long-term financing arrangements and contractual rights, raising questions as to the legitimacy and legality of, and motivations for, some such measures. 

As foreign investors have sought to resist state interference with their investments, this has, in turn, placed a renewed focus and importance on the range of instruments put in place by states themselves to protect foreign investors and their investments. This includes the extensive network of investment protection treaties and contractual stabilisation provisions. The resulting proliferation of investor-state disputes has, in many instances, meant that legal instruments have themselves become controversial.

This Quickguide considers the mechanisms that exist to protect foreign investors and their investments, and how investor-state disputes are resolved.

Mechanisms protecting foreign investors

The key mechanisms offered by states to protect foreign investors, and their investments, are: 

• investment legislation;
• investment contracts; and
• bilateral and multilateral investment protection treaties.

A state may enact domestic investment legislation guaranteeing certain treatment for investors. Such legislation might guarantee exemption from taxation regimes or provide a specific fiscal regime for investors in a particular industry sector. However, investors may be wary of relying solely on these protections, given the risk that domestic legislation can be varied, watered down or revoked entirely, by subsequent governments. Further, such investment legislation often provides for disputes to be resolved before the national courts of the host state. A foreign investor may have concerns about litigating against a state in its own courts.

An investor may enter into an investment contract with a host state. Examples of such contracts in the extractive industries are concession agreements and production sharing contracts, under which investors receive certain protections in return for the significant, long-term investments they make in the exploitation of a state's natural resources. Investment contracts sometimes contain so-called stabilisation clauses, which are designed to protect or insulate investors from changes in law or regulation, which would adversely affect their interests (these are discussed further below). However, such clauses are controversial and their efficacy in the face of government action is variable. Investment contracts often provide for disputes to be resolved by international arbitration seated in a neutral jurisdiction.

States' interest in promoting and encouraging foreign direct investment has also given rise to an extensive network of investment protection treaties. These can take the form of either bilateral investment treaties (BITs), concluded between two states, or multilateral investment treaties (MITs), which are entered into by multiple states. The UN Conference on Trade and Development (UNCTAD) lists more than 2,800 signed BITs, of which over 2,200 are in force.¹ 

Historically, BITs were typically entered into by one traditionally capital-exporting state and one principally capital importing state. However, this dynamic has changed over time, as investment flows have become more complex. MITs vary, with some focused exclusively on investment protection, while others are broader in scope, such as free trade agreements containing an investment chapter. There is often a regional dynamic to MITs' membership. 

BITs and MITs both commonly include provisions that establish specific protections for investors from one state party to the treaty, which make investments in another state party's territory. They also often provide that a foreign investor can seek to enforce those protections directly against the host state by way of arbitration.

There is a fundamental difference between investment legislation and treaties, on the one hand, and investment contracts, on the other. An investor must negotiate with the host state on the terms and protections of an investment contract. By contrast, protections available under an investment treaty or law are typically available to any investor that satisfies the relevant requirements (for example, meets the definition of an "investor"), without the need to negotiate and, sometimes, without the host state even being aware of it.

Investors may have the benefit of one of the above instruments or a combination of instruments. For example, an investor who enters into an investment contract with a host state might also fall within the protections provided for in a BIT. The available protections under each will also differ, meaning that a breach of a term of an investment agreement will not necessarily amount to a breach of a BIT. 

Investment contracts: available protections

Investment contracts between investors and host states (or state entities) typically relate to significant projects, often for the exploitation of a state's natural resources or relating to major infrastructure projects. It follows that they are, by their nature, long-term and usually involve substantial capital commitments, meaning that investors will seek to agree contractual protections covering the lifetime of the project or investment. When that period is measured in decades, it is accepted that legal and regulatory changes will occur but investors seek to insulate their investments from such changes. To achieve this, investment contracts often contain so-called stabilisation clauses. 

Stabilisation clauses are individually negotiated and vary in form and scope. However, they broadly fall into the following categories:

• Freezing clauses. Some of the most frequently adopted stabilisation clauses, these are designed to 'freeze' or fix the host state's national legislation that affects the investor for the life of its investment. Typically, they also provide that any legislation enacted subsequent to the investment contract will not bind the investor. The most controversial type of stabilisation clause, their use has declined in recent times.
• Intangibility clauses. These provide that a host government cannot unilaterally nationalise a project or modify an investment contract. Any changes require the consent of the investor.
• Economic equilibrium clauses. Also known as 'rebalancing the benefit' clauses, these protect investors by providing that, in the event of a change of law which adversely affects the investor, the host government will ensure that the investor is not disadvantaged. This will typically involve specific mechanisms for agreeing compensation for the investor from the host government. Modern stabilisation clauses typically adopt this form.
• Allocation of burden clauses. These are similar to economic equilibrium clauses and provide that, if there is a change in legislation, the burden of such change will be met by the host state, rather than the investor. For example, a production sharing contract in the oil industry might provide that the burden of any tax changes would be carried by the state oil company, rather than the private investor.

An investment contract may also include a hybrid stabilisation clause, which contains elements of the different types of stabilisation clause outlined above.

Stabilisation clauses have attracted widespread criticism, particularly from NGOs, which have alleged that stabilisation clauses impair the ability of states to improve their environmental, health and safety, and human rights regimes. In one high profile case involving the construction of a transnational oil pipeline, international pressure forced investors to enter into a side agreement, promising that they would not enforce stabilisation provisions in a manner that would prevent the host states from improving their human rights legislation. 

BITs and MITs: overview

There is no standard form for a BIT, as each one is individually negotiated between the two state parties. Some states have adopted so-called "model" BITs, which serve as a basis for negotiations. It is, therefore, imperative to carefully review any BIT that you are considering relying on, and to take specialist advice, as even superficially similar treaties can contain subtle variations in language, which fundamentally alter their scope and effect.

It is possible to identify two broad categories of BIT. The first, so-called "old-style" BITs, are relatively straightforward instruments, typically running to around eight to ten pages. They set out definitions, including key terms such as "investor" and "investment", the available investment protections, provisions on investor-state dispute settlement (ISDS), and the term of the BIT. "Newer generation" BITs, concluded from around 2015 onwards, are often more nuanced, with more closely defined protections and, in some cases, limits on ISDS. 

Like BITs, MITs also vary significantly in scope, having been negotiated by multiple state parties, whose interests may not always be aligned. Important MITs include:

• the United State-Mexico-Canade Agreement (USMCA), which in 2020 replaced the well-known North American Free Trade Agreement (NAFTA);
• the Association of South East Asian Nations (ASEAN) Agreement for the Promotion and Protection of Investments between Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam;
• the Protocol of Colonia for the Promotion and Reciprocal Protection of Investments in MERCOSUR, between Argentina, Brazil, Paraguay and Uruguay;
• the Dominican Republic-Central America Free Trade Agreement (CAFTA-DR), between the US, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua and the Dominican Republic; and
• the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP), between Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore, the United Kingdom and Vietnam.

These MITs provide protection for investors on a regional basis, seeking to encourage trade and mutual investment. 

Another significant MIT, and one which provides investor protection on an industry, rather than regional, basis, is the Energy Charter Treaty (ECT). It recognised the interconnected nature of energy and power supplies, and sought to apply investment protections accordingly. The ECT entered into legal force in April 1998 and, at its high point, more than 50 states, as well as the EU and EURATOM, had signed or acceded to the ECT. However, in recent years it became controversial (as discussed further below) and, despite a modernisation programme, various contracting states, as well as the EU and EURATOM, withdrew.

Investment treaty protections

Broadly speaking, BITs and MITs contain similar investor protections. However, even where two treaties make provision for the same type of protection, the scope of those protections may vary significantly. 

The most common protections found in these instruments are:

• protection from expropriation without compensation;
• most favoured nation (MFN) provisions;
• national treatment provisions;
• fair and equitable treatment;
• full protection and security; and
• free transfer of investment and returns.

At the core of most investment treaties is protection from expropriation without compensation. Investment treaties do not prevent a host state from expropriating assets per se. Instead, the aim is to ensure that expropriation should only take place for a public purpose, on a non-discriminatory basis, in accordance with due process, and in return for prompt and effective compensation. Where any of these elements is lacking, the expropriation will be considered unlawful and in breach of the treaty. Expropriation may be indirect, as well as direct. Generally, direct expropriation occurs where the investor's investment is taken through formal transfer of title or outright seizure. Indirect expropriation, which is more common today, is often said to occur where a state takes measures that leave the investor in possession of its property but prevent them from using it in any meaningful way or substantially deprive them of the investment's economic value. An indirect expropriation may be a one-off state measure or a series of acts, the cumulative result of which has an expropriatory effect (a so-called "creeping expropriation").  

An MFN clause provides that investors covered by the relevant treaty are entitled to treatment from the host state which is no worse than that afforded to any investors under other treaties concluded by the host state. The practical effect of an MFN clause is that it may allow a claimant investor under one BIT to rely upon more favourable protections granted by the host state in another BIT or MIT to which it is party. However, the operation of MFN clauses has generated substantial jurisprudence from investment treaty arbitration tribunals. A particular area of controversy is whether MFN clauses apply only to specific treatment, to substantive protections under a BIT or MIT (such as fair and equitable treatment, discussed below), or also to other rights, such as ISDS. 

A national treatment provision can be thought of as the inverse of an MFN clause, and requires the host state to treat a foreign investor covered by the treaty no less favourably than it treats its own domestic investors, who are in a comparable position.

One of the most common, and most commonly relied upon, protections is the requirement for the host state to extend fair and equitable treatment (FET) to foreign investors and/or their investments. There is no single definition of what constitutes FET, but, broadly speaking,  tribunals have found that such provisions prevent host states from taking arbitrary, grossly unfair or discriminatory measures against foreign investments, denying them justice or violating their legitimate, investment-backed expectations. 

A number of BITs and MITs also oblige the host state to provide investors with full protection and security.  Tribunals have found that such clauses create a due diligence obligation on the host state, via its control of law and order authorities, to prevent harm to the physical integrity of the investor and the physical destruction of property owned by it. There is debate as to whether full protection and security obligations extend also to so-called legal protection of the investor and its property. While some treaties include language addressing this, many are ambiguous. Tribunals called on to interpret the full protection and security clauses have arrived at varying results. 

It is also common for investment treaties to provide that an investor is entitled to the free transfer of investment and funds in and out of the jurisdiction in which it has invested.

Resolving investment disputes

Disputes arising under investment contracts will be resolved through whatever dispute resolution mechanism has been agreed in the contract. Commonly, this is international commercial arbitration, however, the parties may have agreed something different, including ICSID arbitration, which is discussed below. For discussion of the key features of arbitration and drafting arbitration agreements, see our Quickguides, Introduction to International Arbitration and International Arbitration Clauses.

Similarly, national investment laws provide for different mechanisms for enforcing the available protections, including litigation before the courts of the host state or arbitration, commonly at ICSID. 

BITs and MITs often provide that an investor, which considers the host state has breached the protections of an applicable treaty, can commence arbitration directly against the state. Just like commercial arbitration, party consent is required. In the BIT or MIT context, the states make a standing offer in the treaty itself to arbitrate investment disputes, which the claimant investor can accept, provided it meets the requirements of the treaty. 

Most investment treaties (and some investment laws and contracts) provide for a mandatory "cooling-off period," which should be observed before a party can commence proceedings in respect of an investment dispute. The aim of these provisions, is to provide an opportunity (usually three to six months) for the parties to seek an amicable settlement of the dispute. The cooling-off period is usually started by the investor sending a written notice (often known as a "trigger letter") to the host state, formally notifying it that the investor considers there is an investment dispute, outlining its details and drawing the state's attention to the relevant treaty or other instrument, and requesting negotiations. 

Most BITs and MITs provide for at least two potential forums for arbitration (in case one of them is unavailable), with it usually being for the investor to elect, when it commences arbitration, which forum to proceed in. Common arbitral forums include:

• arbitration at the International Centre for Settlement of Investment Disputes (ICSID);
• ad hoc arbitration, usually under the United Nations Commission on International Trade Law (UNCITRAL) arbitration rules;
• arbitration under the rules of a specified arbitral institution, with the SCC Arbitration Institute or the International Court of Arbitration at the International Chamber of Commerce (based in Stockholm and Paris, respectively) being common options.

ICSID arbitration is the most widely used ISDS mechanism. It was established by the 1965 ICSID Convention (also known as the Washington Convention), which has been ratified by over 150 states. As at 31 December 2025, ICSID has registered 983 arbitrations under the Convention, of which the vast majority have come in the last 20 years.

Because ICSID arbitration was specifically designed to resolve disputes between investors and sovereign states, it introduced several novel features that set it apart from other forms of arbitration, including:

• ICSID arbitrations are "delocalised". While ICSID is headquartered are in Washington, D.C., which is the default venue for hearings in ICSID arbitrations, they do not have a "seat" of arbitration. It follows that the law of the venue where the arbitration takes place (for example, where hearings are held) has no impact on the proceedings;
• the ICSID Convention creates a self-contained regime, protecting arbitrations from political interference and national courts are not entitled to exercise jurisdiction over ICSID arbitrations;
• ICSID awards can only be challenged before specialised committees, which are also established under the ICSID Convention; and
• each ICSID contracting state is required to recognise awards and to enforce pecuniary obligations imposed by them.

The principal requirements to establish jurisdiction under the ICSID Convention are:

• party consent in writing; and
• the existence of a legal dispute arising directly out of an investment between an ICSID Contracting State² and a national of another ICSID Contracting State.

The requisite consent to ICSID arbitration by a host state may be contained in national investment legislation, an investment contract or an investment treaty.

ICSID arbitration also brings with it increased levels of transparency. The registration of new claims, together with details such as counsel acting for the parties and the appointed arbitrators, are routinely published on the ICSID website. In many proceedings, details of the claim (such as the sector in which the claim arose and the instrument under which it is brought) are also made public, often with copies of tribunals' procedural orders and awards.³

Present controversy and criticism

ISDS is controversial. By their nature, investment disputes involve, on the one hand, a state (or at least a state entity) and public funds, and, on the other, a private investor, often a large commercial entity. The sums involved are typically substantial, with damages awarded to successful investors exceeding US$100 million in a quarter of all known investment treaty arbitrations.⁴ Many NGOs and other interest groups, as well as a number of states that have faced treaty claims, allege that the system unfairly favours the commercial interests of private investors, as well as fuelling uncertainty and inconsistency in international law. While this is not borne out by the available statistics,⁵ and, despite attempts to "depoliticise" the field and increase transparency, such perceptions persist. 

Other claims include that investment protection provisions in treaties and investment contracts have a so-called "regulatory chill" effect and hamper efforts to combat climate change, by allegedly enabling claims by fossil fuel investors. A number of the states that have withdrawn from the ECT have cited this among their reasons for leaving. However, it is interesting to note that the majority of ECT claims to date have related to changes by states to their regulatory frameworks for renewable energy investments.

Consequently, many newer generation BITs and MITs increasingly provide for narrow definitions of the protections granted and broad carve-outs limiting judicial review. 

Recurring legal issues in investment disputes

Investors and investments

The definitions of investment and investor in investment law are of fundamental importance. If there is no "investment," as defined by the relevant BIT or MIT, or the would-be claimant does not meet the definition of an "investor," it will be unable to gain redress for an act by the host state. 

Investment treaties typically define investments very broadly, using words like "every kind of asset owned or controlled directly or indirectly by an investor." This is commonly accompanied by a non-exhaustive, illustrative list of things that may be expected to qualify as an investment, including rights to movable and immovable property, shareholdings, claims to money and IP rights. 

If the dispute is to be resolved in ICSID arbitration, the investor will also have to satisfy the jurisdiction requirements arising under the ICSID Convention itself, which requires that there be a dispute arising "directly out of an investment". The Convention does not, however, define "investment," which has given rise to significant case law. While some tribunals have simply deferred to the definition of investment in the instrument containing the state's consent to arbitration, others have found that the term "investment" implies certain inherent characteristics that must be met, in particular a commitment of funds by the investor, for a certain duration, with an assumption of risk and a contribution to the economic development of the host state.6 Known as the "Salini criteria," these are often referenced, but cannot be considered definitive. 

Denial of benefits

The definition of "investor" gives rise to the potential for forum shopping. This is where an investor incorporates a company in a specific jurisdiction for the sole purpose of holding their investment through that corporate vehicle to gain the protection of an investment instrument. There is nothing inherently unlawful about this, however, some BITs and MITs contain a so-called denial of benefits clause, which allows the host state to deny the benefits of the treaty to "shell" companies, which are controlled by third-state investors and have no real business in the other state party to the treaty. 

Umbrella clauses

Protection under BITs and MITs exists independently of any contractual rights, which investors may have against the host state. It follows that a treaty breach may be established without any breach of contract and, vice versa, that a breach of contract may not, of itself, be sufficient to establish a violation of an applicable BIT or MIT. However, where a treaty contains an umbrella clause, the picture becomes more complex.

Umbrella clauses generally provide that a host state will observe and abide by any legal obligation that it has entered into with investors of another state party to the treaty, or in relation to their investments. Such clauses are also referred to as "observance of undertakings" clauses and their drafting varies widely. 

Investors frequently argue that the effect of an umbrella clause is to "elevate" a claim for breach of contract into a claim for breach of the investment treaty, so as to gain the protections and remedies available under the relevant treaty. States frequently respond that a breach of contract only entitles an investor to the contractual remedies available under the law applicable to the contract.

Caution should be exercised when reviewing how investment arbitration tribunals have interpreted umbrella clauses. The drafting of umbrella clauses differs and one investment treaty may contain very different provisions to another, while arbitral decisions on the issue are also inconsistent. In one case, for example, the tribunal refused to elevate a contractual breach into an investment treaty breach, ruling that, due to the far-reaching, and potentially very burdensome, implications of such a finding, very clear treaty language would be required, demonstrating that that was the states' intention.⁷ Another tribunal, albeit interpreting a different BIT, adopted a more expansive approach, ruling that the relevant umbrella clause would be meaningless if it did not have the effect of elevating the relevant contractual breach into a treaty breach.⁸ Several other tribunals have adopted this latter approach. 

Current practice suggests tribunals will likely interpret the text of any umbrella clause strictly and several have also required the investor to demonstrate that the alleged breach of an undertaking by the state involved an exercise of sovereign authority, rather than purely commercial activity.⁹

"Cooling-off periods"

The "cooling-off periods" commonly found investment treaties, which provide for a mandatory period during which the investor and host state should attempt to negotiate an amicable settlement before arbitration is commenced, are simple in theory. In practice, issues have arisen where investors have commenced arbitration before expiry of the cooling-off period and arbitral tribunals have not been consistent in their treatment of these instances. 

In some cases, tribunals have held compliance with cooling-off periods to be pre-conditions to the state's consent to arbitration, meaning that a failure to comply deprived the tribunal of jurisdiction over the dispute.¹⁰ However, other tribunals have taken a more pragmatic approach. In one decision, for example, the tribunal held that, while the cooling-off provision was important, it should not acquire "totemic importance," where it was clear that no settlement would be achieved and the BIT required "only that an avenue for a potential settlement is meaningfully stood up".¹¹

Given these inconsistencies, and the potential risks, absent some exceptional urgency, it is advisable for potential claimants to respect cooling-off periods and avoid any jurisdictional risk. 

Interaction with other legal remedies and forums

The underlying contract or the investment treaty may require a claimant to exhaust local remedies before investment arbitration can be commenced. In practice, this usually means that the claimant must bring proceedings first in the local courts of the host state, which can cause delay. It also creates complexities because, in some instances, the available causes of action in the local courts will not reflect those available under, for example, an applicable BIT.

It is important to consider any such requirements together with other restrictions, such as limitation periods. The USMCA, for example, requires that an investor initiate proceedings before a court or administrative tribunal of the host state before resorting to investment arbitration. The investor must wait until either a final decision is delivered or participate in proceedings for 30 months before it can commence arbitration. However, the USMCA also imposes a four-year time bar on claims, beginning from the date the investor acquired, or should have acquired, knowledge of the alleged breach. The operation of these two provisions in practice may mean that there is only an 18-month window in which to commence investment arbitration.

Some treaties also contain fork in the road provisions, which can cause issues. These provide that, once a particular dispute resolution mechanism is chosen, it is not possible to select another. So, if an investor commences proceedings in the local courts in compliance with any (contractual) requirement to exhaust local remedies, it may lose any rights it has to raise the same dispute in arbitration. The ECT contains such a clause. To assess whether a fork-in-the-road clause is engaged, some tribunals have applied a "triple identity" test, which requires an analysis of the identity of the parties, the object in dispute and the cause of action.¹²

Some modern investment treaties, commonly those with the US or Canada as one of the state parties, require a party commencing investment arbitration to file, with its request for arbitration, a waiver of its right to bring any claims before the local courts. This is the case under the US-Peru Trade Promotion Agreement, for example. Decisions under that treaty have been inconsistent in whether a non-compliant waiver (which seeks to carve out or reserve certain rights) amounts to a jurisdictional issue, depriving the tribunal of jurisdiction over the claim, or a curable admissibility issue.¹³

Careful reading of both the underlying contract and any applicable investment treaty is, therefore, essential.

Practical steps to maximise available protections

Parties considering an investment overseas should ask themselves the following practical questions:

• which investment instruments exist in relation to investments in the state;
• if investment legislation is in place, does the duration of the contract lead to concerns that this legislation might change over time;
• can the investment be structured to bring it under the protective umbrella of a BIT or MIT;
• if structuring the investment in this way, ensure that the relevant criteria in the applicable treaty cover the specific investment, including, for example, the definition of investor and investment, and the terms of any denial of benefits clause;
• what are the provisions for dispute resolution under the relevant instrument, and are there any features of it to be aware of (for example, a "cooling-off period" or a requirement to exhaust, or waive access to, local remedies);
• if the instrument provides for ICSID arbitration as an option, will the investment fall within the provisions of the ICSID Convention and are the parties from ICSID Contracting States; and
• if contracting with the host state or a state entity, is it feasible to seek a waiver of sovereign immunity?