Ukraine and Russia: A summary of international legal issues – Christopher Ward SC

This piece was originally published on Substack and is reproduced with the author’s permission.

As Russia continues to wage a war of aggression it is appropriate to deal with the international law applicable to the situation.

Russia has historically laid claims to, and at times controlled, the territory that encompasses modern Ukraine.  Those historical positions are irrelevant.  Ukraine is a fully recognized independent State with full membership of the United Nations, and full international recognition as a State, including recognition from Russia following the dissolution of the USSR.

It follows unambiguously that Russia is engaged in a naked war of aggression.  That war breaches Article 2(4) of the United Nations Charter:

“All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.”

Russian claims to be exercising a form of “protection” in the face of a Ukrainian “genocide” in breakaway provinces are factually ludicrous and are a pathetic, transparent, utterly craven misinformation device.  The international community has overwhelmingly and correctly rejected that pretext.

Ukraine is entitled to exercise a right of individual self defence.   That it is doing with grit and determination.

Other States are also free to join with Ukraine in acts of collective self defence following an armed attack on the territory of a UN member State.  Article 51 of the UN Charter makes that explicit:

“Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security. Measures taken by Members in the exercise of this right of self-defence shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security.”

The Security Council is granted by Article 24(1) of the Charter “primary responsibility” for the maintenance of international peace and security.  That primary responsibility is not exclusive of the rights of individual or collective self defence.  

The Security Council is obviously and effectively paralyzed when a permanent member with veto powers abrogates the trust given to it by the Charter and becomes an aggressor State.  A draft resolution condemning the invasion was the subject of a Russian veto on 26 February.

In those circumstances the right of collective self defence is unrestricted.

All UN member States are therefore free to provide military and non-military assistance to Ukraine, including the possibility of providing military forces on the ground, military equipment and materiel, assistance with supply chains, the provision of land bases, the imposition of sanctions and the use of assertive cyber attacks to disrupt Russian communications.

Calls have been made to impose a no-fly zone over Ukraine.  No fly zones previously have been put in place pursuant to resolutions of the Security Council.  That option is not practically available here.  Any no-fly zone operation would be seen by Russia as a direct military intervention by third States in the war, and Russia’s response, given the state of mind of Mr Putin which seems entirely unconstrained by law or morality, could escalate the world into immediate and dangerous conflict. 

However it is clear that any decision to engage in that way with Russia in Ukrainian airspace would be legal.

International law recognizes a crime of aggression.  The Rome Statute of the International Criminal Court was amended in 2018 to include within the jurisdiction of the Court the crime of aggression.  However that particular jurisdiction extends only to the States party to the Rome Statute.  Neither Ukraine nor Russia are parties and therefore the International Criminal Court will not have express jurisdiction in relation to the crime of aggression.

The International Criminal Court will however have jurisdiction in relation to crimes against humanity and war crimes committed in the territory of Ukraine.  That is because Ukraine has (without becoming a full party to the Rome Statute) made two declarations under Art. 12(3) of the Rome Statute which accept the exercise of ICC jurisdiction in relation to war crimes and crimes against humanity committed on its territory at any time after November 2013, and again from February 2014. Because those declarations referred in terms to situations then in existence, Ukraine should consider updating its Declaration as a matter of urgency, even while the military conflict continues.   

It is likely that individuals, including Russian soldiers, who engage in such international crimes in the territory of Ukraine will be the subject of prosecution in years to come.

Although the jurisdiction of the International Criminal Court to prosecute Mr Putin and other Russian leaders for the crime of aggression is unavailable, the prohibition upon the use of force and aggression is firmly established as a rule of customary international law.  Many States have domestic laws enabling prosecution under doctrines of universal jurisdiction for crimes against humanity, and those laws will be enlivened by these events.

At this stage it should be hoped that the strength of Ukranian defence and the relative solidarity of the international community will lead Russia to a negotiating position sooner rather than later.  There is no justification in international law for any negotiation to recognise any permanent Russian occupation of Ukranian territory.

A war of aggression commenced by a major power with control of the Security Council is the nightmare scenario for the power structures of international law.  The global response to this situation will not only determine the outcome of the military conflict but will most likely lead to a search for more permanent collective self defence structures to reduce reliance upon the Security Council which is no longer capable of dealing with current threats to international peace and security.

Dr Christopher Ward SC is Senior Counsel, NSW Bar, Sydney, Australia, Honorary Professor, Australian National University, Canberra and Immediate Past President, International Law Association.

Suggested citation: Christopher Ward, ‘Ukraine and Russia: A summary of international legal issues’ on ILA Reporter (8 March 2022) <>