On Wednesday the Commons will be asked to approve RAF strike missions against ISIL/Daesh targets inside Syria. LDV readers will be familiar with Tim Farron's five tests but here I'm going to focus only on the first: would such strikes be legal?
(NB. If it is, each target would be subject to the normal targeting rules of proportionality - ie, the use of force must be proportionate to the military advantage to be gained, and discrimination, - ie, that you may only attack military and not civilian targets.)
A little history first. The use of force between states had been a normal part of diplomacy throughout history until 1945, when aggression was banned by the UN Charter under Article 2(4), which reads:
"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."
This was revolutionary, and whilst it has not stopped conflict since 1945, it has provided a legal basis for acting against aggression when there is international agreement - Korea in 1950 and Iraq in 1991 being the prime examples.
There are three exceptions to this rule. The first is when the Security Council authorizes the use of force. This is allowed under Article 42, in Chapter VII of the Charter. The second is self-defence, including collective self-defence, in Article 51, also in Chapter VII. In the words of the UN itself: "Article 51 of the Charter provides an exception to the prohibition of the use of force as stipulated in Article 2 (4)".
The third is the humanitarian exception, known as Responsibility to Protect (R2P) which provides regional organizations with the right to use force without Security Council authorization to stop humanitarian disasters. However, R2P is not relevant here.
The RAF is already conducting airstrikes in Iraq against ISIL/Daesh targets at the request of the Iraqi government. This is unambiguously legal, as it is an act of collective self-defence under Article 51. In my view, the Iraqi request would also extend to attacking ISIL/Daesh targets in Syria which are directly contributing to ISIL/Daesh military activity in Iraq, though the UK Government has not elected to extend the RAF's airstrikes in this way.
There was surprise in September when Reyaad Khan was killed by an RAF strike in Syria, not because he was involved in ISIL/Daesh attacks in Iraq, but because he allegedly was plotting attacks in the UK. This was justified by the UK as self-defence under Article 51. You will note that the UK letter claims that Mr. Khan represented an "imminent" threat, reflecting the so-called Caroline test, where the need for a pre-emptive action must be "instant, overwhelming, leaving no choice of means, and no moment of deliberation". It is for the Government to demonstrate that this was the case in the attack that killed Mr. Khan, otherwise that specific attack would have been an illegal use of force.
Thus, prior to the adoption of UN Security Council Resolution 2249 on 20 November 2015, it would've been legal in my view for the RAF to attack ISIL/Daesh targets in Syria if they were directly contributing to military activity in Iraq, or in the much narrower case of a truly imminent threat to the UK.
Paragraph 5 of UNSCR 2249 sets out the Security Council's authroisation for the use of force. It reads in part:
"Calls upon Member States that have the capacity to do so to take all necessary measures, in compliance with international law, in particular with the United Nations Charter, as well as international human rights, refugee and humanitarian law, on the territory under the control of ISIL also known as Da'esh, in Syria and Iraq"
It does what it says: UN Member States - obviously including the UK - are authorised to attack ISIL/Daesh targets across Syria. Therefore, the difference before and after UNSCR 2249 is simple: to be legal, the UK no longer has to demonstrate a nexus with Iraq or the UK.
With the passage - unanimously - of UNSCR 2249 on 20 November, I believe that, subject to the proportionality and discrimination tests, RAF strikes on ISIL/Daesh are legal anywhere in Syria and Iraq.
* Toby Fenwick is a member of the party in Putney, and is former research associate with CentreForum, specialising in international affairs. He holds an LLM from University College London in international law, with a specialisation in use of force questions, and an MSc in international relations from the LSE.









