41-year-old Jesse Schust, from north London, said the written judgment meant far more to him than the £4,800 damages he received.
Speaking outside the court, he said: "For me it's a tremendous relief to have a vindication after 10 years that the treatment that we received from the police was wholly unjustifiable.
"It's deeply upsetting to know that the police had many opportunities to make other choices and it appears that they stuck to a pre-set plan because of faulty intelligence."
Police breached the rights of campaigners by stopping them from attending a mass rally against the Iraq war in Gloucestershire, a judge has ruled.
Up to 159 protesters left London on coaches to attend the demonstration at RAF Fairford two days after the coalition forces launched their assault from the airbase in March 2003.
But they were stopped at Lechlade, a few miles short of the airfield, and sent back to the capital.
Judge David Mitchell, sitting at Central London County Court, ruled that Gloucestershire Police breached protesters' rights to freedom of expression and freedom of peaceful assembly after hearing 12 test cases brought by campaigners.