A White Paper published in 2008 proposed that MPs should be given the final say on whether British troops should be sent to war - stripping the Prime Minister of his war-making powers under the so-called Royal Prerogative.
This has been a running sore within the Labour Party since Britain went to war in Iraq in 2003. On the eve of the invasion, Tony Blair did set a parliamentary precedent by allowing a vote in the Commons - but later attempts to make this a permanent arrangement were dismissed out of hand.
Now, though, the government has changed its mind - and Gordon Brown is proposing that MPs should have the final word.
Ministers say this can be done without changing the law but instead through a simple vote on a resolution in the Commons. But no date has been set.
