One of Britain’s leading barristers in corporate and international litigation testified on Tuesday that he thought it would be illegal for the U.K. to join in the 2003 invasion of Iraq, but later changed his mind.

Lord Peter Goldsmith, now chair of European litigation at Debevoise & Plimpton, served as the U.K.’s attorney general and a top legal adviser to former British Prime Minister Tony Blair from 2001 to 2007. Goldsmith’s testimony came before a five-person British panel investigating the legality of the Iraq war. (Click here for video of Goldsmith’s testimony, courtesy of the BBC.)