Ken Livingstone has said he was "unsurprised" by the High Court's decision to block a bid to prosecute Tony Blair.
In July, the court judges dealt with a charge brought by a former Iraqi army Chief of Staff, General Abdul Wahed Shannan Al Rabbat.
Rabbat claimed the former Prime Minister committed a crime of aggression in opting to invade Iraq to overthrow Saddam Hussein. But his lawyers didn't convice the High Court Justices, who said the case had no prospect of succeeding as the crime alleged by Rabbat did not exist in British law.
Livingstone - the former Mayor of London - said this outcome wasn't particularly unexpected.
He told George Galloway: "I was disappointed, because I do think there should be a proper trial.
"I wasn’t surprised because our judiciary were unlikely to turn all of this over. It’s a very establishment judiciary, not as bad as 30 years ago, but still fairly tied up.
"There’s only two countries in the world who don’t have a written constitution, Britain and Israel. The government and judges of the day make it up as they go along. If we had a written constitution, it might have been a different decision.
"This is our problem; we’ve got a huge establishment, the oil industry behind all of it. For every war in the Middle East in our lifetime, it’s about the west having control or some predominance over the oil in the Middle East."
Livingstone said details of a critical report by the US Congress might have ensured the invasion might never have took place.
He said: "They [Congress] published their report just before the Americans and British Parliament had to decide on whether or not to go to war.
"But 28 pages were held back and never published until they came out about a year ago. Those 28 pages are a damning indictment the main source of funding for 9/11 was Saudi Arabia, not Iraq.
"If that had been published, Blair wouldn’t have been able to win the Parliamentary vote and Bush wouldn’t have won the vote in congress. The truth was suppressed and withheld."