Consent in International Law

Meaning of Consent

Consent is one of the recognised circumstances precluding wrongfulness under the law of State responsibility.

Under Article 20 of the International Law Commission’s Articles on Responsibility of States for Internationally Wrongful Acts (ARSIWA), valid consent by a State to the commission of a particular act by another State precludes the wrongfulness of that act in relation to the consenting State, to the extent that the act remains within the limits of that consent.

In simple terms:

Valid consent + conduct within the scope of consent = wrongfulness is precluded

Consent therefore operates as an exception to the ordinary rule that conduct contrary to an international obligation gives rise to State responsibility.

Article 20 of ARSIWA

Article 20 provides:

“Valid consent by a State to the commission of a given act by another State precludes the wrongfulness of that act in relation to the former State to the extent that the act remains within the limits of that consent.”

There are therefore three central requirements:

• Consent must be valid.
• It must relate to the particular act concerned.
• The conduct must remain within the limits of the consent.

Rationale Behind Consent

International law recognises the autonomy and sovereign equality of States.

A State may, within the limits permitted by international law, agree to conduct by another State that would otherwise interfere with an interest or obligation owed to it.

For example, a State may consent to:

• entry of foreign military personnel into its territory;
• use of its territory for a particular purpose;
• a particular form of assistance or intervention;
• conduct that would otherwise violate a bilateral obligation owed to it.

The consent does not necessarily make the conduct universally lawful. It operates in relation to the consenting State and within the scope of the consent.

Conditions for Valid Consent

Consent Must Be Valid

The first requirement is that the consent must be legally valid.

Consent obtained through circumstances that invalidate the State’s legal will cannot automatically be treated as valid consent under Article 20.

The validity of consent must therefore be assessed in light of the applicable rules of international law.

Consent Must Be Given by the State

The consent must be attributable to the State itself.

It should be given by an authority competent to express the State’s consent in the circumstances.

The precise authority required may depend upon:

• the nature of the conduct;
• the constitutional and legal arrangements of the State;
• the applicable rules of international law.

Consent Must Relate to a Particular Act

Article 20 refers to consent to a “given act.”

Therefore, consent should be sufficiently specific to the conduct in question.

A general statement of friendship, cooperation or political support does not automatically constitute consent to every act that another State might undertake.

Consent Must Exist Before or at the Relevant Conduct

Consent must be relevant to the conduct for which its legal effect is claimed.

A State cannot simply assume that another State has consented.

The existence and scope of the consent must be established from the circumstances.

Limits of Consent

One of the most important phrases in Article 20 is:

“to the extent that the act remains within the limits of that consent.”

This means consent is not unlimited.

If State A gives State B permission to undertake a particular activity, State B cannot automatically use that permission for unrelated conduct.

Example

State A permits State B’s armed forces to enter its territory solely for humanitarian assistance.

If State B uses the permission to conduct military operations unrelated to the humanitarian mission, the additional conduct falls outside the scope of the consent.

Therefore:

Consent to Act A ≠ Consent to Act B

Partial Consent

Consent may cover only part of the conduct.

Where conduct exceeds the authorised scope, Article 20 may preclude wrongfulness only to the extent that the conduct was actually authorised.

Thus, consent can operate partially.

Example

State A permits State B to enter a specified area for seven days.

If State B:

• enters the authorised area for seven days → consent may apply;
• enters additional areas → outside the consent;
• remains for an additional month → outside the consent.

The conduct exceeding the permission must be assessed independently.

Consent and Sovereignty

Consent is particularly important in relation to territorial sovereignty.

A State’s consent can permit conduct on its territory that would otherwise interfere with its sovereign rights.

For example, a State may permit:

• foreign troops to enter its territory;
• foreign aircraft to use its airspace in specified circumstances;
• foreign vessels to enter particular areas;
• foreign authorities to undertake a specific operation.

Because the territorial State has consented, the conduct may not be wrongful in relation to that State, provided the conduct remains within the consent.

Consent Does Not Automatically Affect Third States

A critical examination point is that Article 20 speaks of wrongfulness “in relation to the former State”—the State giving consent.

Therefore, consent given by State A to State B does not automatically eliminate B’s responsibility towards third States.

Example

State A permits State B to undertake an operation on A’s territory.

If that operation also violates an independent international obligation owed by State B to State C, A’s consent does not necessarily eliminate B’s responsibility towards C.

Therefore:

Consent operates within the legal relationship affected by the consent; it is not a universal waiver of international obligations.

Consent and Jus Cogens

Consent cannot be used to justify conduct contrary to a peremptory norm of general international law (jus cogens).

This follows from the general limitation in Article 26 ARSIWA.

A State cannot simply consent to another State’s violation of a jus cogens obligation and thereby make the violation lawful.

Example

A State’s consent cannot provide a legal justification for conduct that violates a peremptory prohibition such as genocide or torture.

Thus:

Consent → subject to higher rules of international law

Consent and Treaty Obligations

Consent should also be distinguished from consent given in the context of treaty-making.

A State may consent to be bound by a treaty, but Article 20 concerns something more specific: consent by one State to the commission of a particular act by another State.

Therefore, these are conceptually different:

Consent to be bound by a treaty

≠

Consent to particular conduct under Article 20 ARSIWA

Consent vs Waiver

Consent and waiver can sometimes appear similar, but they should not be treated as identical.

Consent

Consent is an authorisation of particular conduct.

It may prevent that conduct from being wrongful in relation to the consenting State.

Waiver

A waiver generally involves a State relinquishing or foregoing a legal claim or right.

For examination purposes:

Consent → permission for conduct

Waiver → relinquishment of a claim/right

Consent vs Acquiescence

Consent should also be distinguished from acquiescence.

Consent involves an affirmative authorisation or legally effective agreement.

Acquiescence generally refers to a State’s conduct or silence in circumstances where its behaviour may amount to acceptance.

Silence should not automatically be treated as consent.

The circumstances must establish whether the State actually gave legally relevant consent.

Consent vs Self-Defence

Consent	Self-defence
Article 20 ARSIWA	Article 21 ARSIWA
Based on permission by the affected State	Based on the right of self-defence
Concerned with a particular act	Concerned with lawful defensive measures
Must remain within the scope of consent	Must comply with the UN Charter and international law
Cannot justify violation of jus cogens	Cannot justify violation of jus cogens

Consent vs Countermeasures

Consent	Countermeasures
Article 20	Article 22
Based on prior permission	Based on a prior internationally wrongful act
Conduct is authorised within the scope of consent	Conduct is permitted as a lawful response under strict conditions
Does not require a prior wrongful act	Requires a prior wrongful act by the target State
Must remain within consent	Must satisfy countermeasure requirements

Consent vs Necessity

Consent	Necessity
Article 20	Article 25
Based on another State’s valid permission	Based on protection of an essential interest
Focuses on authorisation	Focuses on grave and imminent peril
Requires valid consent	Requires the conduct to be the only way to safeguard the interest
Limited by the scope of consent	Strictly limited by Article 25

Consent and the Law of State Responsibility

Consent fits into the broader framework of Article 2 ARSIWA.

Normally:

Attribution

Breach of international obligation

↓

Internationally wrongful act

But where Article 20 applies:

Conduct attributable to State

↓

Conduct appears inconsistent with an international obligation

↓

Valid consent exists

↓

Conduct remains within scope of consent

↓

Wrongfulness is precluded

Therefore, consent does not deny that the conduct occurred. It affects its legal character as wrongful conduct.

Important Exam Illustration

Imagine:

State A allows State B to station 100 troops on its territory for a joint humanitarian operation.

State B stations the troops in accordance with the agreement.

There is no wrongfulness in relation to State A because:

• State A gave consent;
• the consent was valid;
• the conduct was specific;
• the conduct remained within the authorised scope.

Now suppose State B:

• sends 5,000 additional troops;
• occupies additional territory;
• conducts military operations unrelated to the authorised activity.

The additional conduct may fall outside the scope of consent.

This illustrates the most important principle:

Consent only precludes wrongfulness to the extent that the conduct remains within its limits.

Key Legal Principle

The doctrine can be remembered through the formula:

VALID CONSENT

↓

PARTICULAR ACT

↓

WITHIN THE AUTHORISED LIMITS

↓

WRONGFULNESS PRECLUDED

↓

ONLY IN RELATION TO THE CONSENTING STATE

↓

SUBJECT TO JUS COGENS

Quick Revision

Point	Rule
Provision	Article 20 ARSIWA
Nature	Circumstance precluding wrongfulness
Basic principle	Valid consent can preclude wrongfulness
Consent must be	Valid
Subject matter	A given/particular act
Limitation	Act must remain within the limits of consent
Scope	Operates in relation to the consenting State
Third States	Consent does not automatically affect obligations owed to third States
Jus cogens	Consent cannot justify violation of a peremptory norm
Related provisions	Articles 21–27 ARSIWA

One-Line Exam Answer

Under Article 20 ARSIWA, valid consent by a State to a particular act by another State precludes the wrongfulness of that act in relation to the consenting State, to the extent that the act remains within the limits of the consent.

Conclusion

Consent is the first circumstance precluding wrongfulness recognised under ARSIWA. It reflects the principle that a State may, within the limits permitted by international law, authorise another State to undertake particular conduct that would otherwise be wrongful in relation to it.

However, consent must be valid, specific and limited in scope. It cannot be presumed merely from silence or general cooperation, and it cannot authorise conduct contrary to jus cogens. Most importantly, Article 20 operates only to the extent that the conduct remains within the limits of the consent.

For examination purposes, remember:

Article 20 → Valid Consent → Particular Act → Within Limits → Wrongfulness Precluded