(Note that this text is not intended as an exhaustive analysis of UN Security Council (UNSC) authority, but as a quick reference to accompany considerations of an International Atomic Energy Agency (IAEA) referral to the UNSC of the Iranian nuclear matter.)

As mentioned in articles linking to this text, the UNSC is a partner with the IAEA within the UN system and directly or indirectly can bolster and augment the IAEA’s legal authority and investigative activities.  The UNSC has wide-ranging discretion to adopt nonmilitary means to address threats to international peace and security, of which economic sanctions are but one example.  Investigative activities are another.  Even if Iran withdrew from the nuclear Non-Proliferation Treaty (NPT) one easily could argue that the UNSC in its judgment could still require Iran submit to IAEA oversight, or any other kind of oversight deemed necessary.

UNSC flexibility, nonmilitary options

The UNSC has more flexibility under the UN Charter than might be commonly understood, and certainly much more than the IAEA.  For example, while the UNSC has broad authority to address matters impacting peace and security, including varying degrees of force, there are no actual limits in the text on the UNSC’s range of nonmilitary options.  Sanctions are held out as one possibility, not a limitation on what the UNSC can do.

Under UN Charter Article 39, the UNSC shall assess threats and decide the best measures for responding to them:
 

Article 39
 

The Security Council shall determine the existence of any threat to the peace, breach of the peace, or act of aggression and shall make recommendations, or decide what measures shall be taken in accordance with Articles 41 and 42, to maintain or restore international peace and security.

In turn, Article 41 provides that the UNSC “may decide what measures not involving the use of armed force are to be employed to give effect to its decisions.”  Economic sanctions are presented merely as one possible option:

The Security Council may decide what measures not involving the use of armed force are to be employed to give effect to its decisions … These may include complete or partial interruption of economic relations and of rail, sea, air, postal, telegraphic, radio, and other means of communication, and the severance of diplomatic relations.

(emphasis added)

To reiterate, Article 41 therefore grants the UNSC broad discretion to determine the best means for addressing a threat and mentions economic sanctions as one option.

There is no indication under Article 41 that nonmilitary measures could not include, for example, wide-ranging inspections on demand.  The UNSC could require such measures if its judgment calls for it as the appropriate means to defuse a threat, and, for example, look to sanctions to enforce compliance.  Such measures, delegated to the IAEA, also would dovetail with the UNSC’s investigatory powers under Article 34.

The result is that even if Iran withdrew from the NPT, there is an argument that the UNSC could still require that Iran submit to IAEA oversight, or any other kind of oversight necessary to further international peace and security.

UNSC investigative powers

Article 34 clearly empowers the UNSC to investigate matters impacting peace and security and places no explicit limit on the intrusiveness of such inquiries:

Article 34

The Security Council may investigate … any situation which might lead to international friction or give rise to a dispute, in order to determine whether the continuance of the … situation is likely to endanger the maintenance of international peace and security.

(emphasis added)

Even in the absence of Article 34, of course, the UNSC’s broad authority under other provisions, such as Article 39, clearly still would encompass investigative activities.

Force

Article 42 relates to the use of force but also makes clear that force is not an option of first-consideration:

Article 42
 

Should the Security Council consider that measures provided for in Article 41 would be inadequate or have proved to be inadequate, it may take such action by air, sea, or land forces as may be necessary to maintain or restore

international peace and security. Such action may include demonstrations, blockade, and other operations by air, sea, or land forces of Members of the United Nations.

As can be seen, Article 42 does not provide for the use of force as a free-standing power or as an option of first-consideration, but only frames the use of force in relation to nonmilitary options.  Article 42 would condition any use of force, including blockades, upon a UNSC determination that nonmilitary alternatives were inadequate or would be inadequate.  Moreover, Article 42 limits such action to a specific targeted goal of maintaining or restoring international peace and security, perhaps as opposed to serving some other policy goal.  It therefore could be argued that Article 42 action must dovetail with a principal of proportionality.

Further reading:

 
Charter of the United Nations, http://www.un.org/aboutun/charter/