May can take military action without first asking MPS

Constitutionally speaking, there is no need for the Prime Minister to seek permission from Parliament to take military action. The Cabinet serves at Her Majesty’s pleasure and exercises executive power on her behalf. That includes launching military action and declaring war. This is known as the “royal prerogative”.

But of course, Parliament has had a role in the past. While Britain does not have a codified constitution, there is still a careful balance of powers. If the Cabinet were to act willy-nilly then Parliament would have something to say about it, and Parliament is ultimately sovereign.

During the twentieth century, the extent to which any government consulted Parliament to’d and fro’d. What never took place was a vote by MPS to authorise military action before it was launched.

That changed in 2003 with the second Iraq war, when Tony Blair chose to put the decision to Parliament. Still, that government held out that a convention had not been created. Blair also told a Commons committee in 2006: “I cannot conceive of a situation in which a government … is going to go to war except in circumstances where militarily for the security of the country it needs to act immediately without a full parliamentary debate.”

The Cabinet Manual was amended to acknowledge “that a convention had developed in Parliament that before troops were committed the House of Commons should have an opportunity to debate the matter”, unless “there was an emergency”.

For the Libya intervention in 2011 Parliament was asked to vote on the intervention after it had begun. The real turning point was in August 2013, when the government suffered a defeat over plans to bomb the Syrian regime in retaliation for a chemical weapons attack. For many MPS, this was a clear statement by Parliament of its sovereignty and of the existence of a convention.

So does the PM have to consult Parliament first? Not quite. First, what constitutes an “emergency” is almost impossible to define. Second, it is still just a convention with no legal standing. In fact, the Government could, in theory, simply ignore a vote by Parliament against military action, because of the royal prerogative. If Parliament really wants to tie the Government’s hands then it needs to place the convention on the statute books.

Mrs May will probably get away with not consulting Parliament this time. She will eventually have to make a statement to the House and seek its permission for any prolonged engagement. Otherwise, she will find herself in deep constitutional water.