Two senior Labour MPs who backed the war with Iraq have criticised Tony Blair for basing so much of his case on weapons of mass destruction.
Mr Soley thinks the case for regime change should have been made more strongly
Ann Clwyd and Clive Soley say the prime minister should have made more of what they see as the case for regime change.
Mr Soley called for a change in international law to permit ousting "psychopathic killers" who rule failed states.
The world was not a safe place if "people like that" were left in power.
Mr Soley told BBC Radio 4's Today programme that Mr Blair's case for war early on was wider than WMD - an issue that became increasingly central to his argument as time went on.
"Now I understand why, the media was particularly interested in that and not surprisingly and not least because Tony Blair emphasised that so much," said Mr Soley.
"Our case is that there is a case for regime change in these extreme cases of failing states and the key is to find a way in which the UN can legitimise intervention and regime change because we cannot go on in the 21st century accepting that somehow or other it's alright to turn a blind eye to these psychopathic killers who do take over nation states."
Mr Soley said in order for intervention to be legitimised a change in international law would be necessary.
"I think that one of the things that people have to take on board is that none of us are safer if we leave people like this in power not only because they brutalise their own society, their own people ... but they destabilise their whole region and with the existence of weapons of mass destruction, the danger becomes much greater.
"The difficulties of controlling the situation become almost impossible."
Mr Soley acknowledged that in the past people like Saddam Hussein had received backing from Britain and America.
But he argued that in those days the Cold War meant that Western policy was often responding to what the Soviet Union was doing - if the Kremlin backed Iran, the Pentagon backed Iraq.
The MP said just because brutal dictators had be supported by such policies in the past did not mean they could be justified in the future.
Ms Clwyd is Mr Blair's special representative to Iraq and argued the case for toppling Saddam on the basis of his human rights record.