British Prime Minister Tony Blair was excused on Tuesday from answering a court summons to appear in the woman's case.
Pat Blackburn's son-in-law Les Hehir, 34, a sergeant in Britain's Royal Artillery, was killed when a US Sea Knight helicopter he was aboard crashed south of the Kuwait border on 21 March 2003.
Blackburn, who was taken to court on Tuesday after withholding $27,348 in tax payments in protest against the war, told Weymouth County Court, in southwest England, that she had refused to pay the tax because Blair had failed in his promise to send her evidence of Saddam Hussein's weapons programme.
"If I wasn't here and had I been a good citizen and paid my tax bill I would never hear from Tony Blair again.
"I have no conscientious objection to paying tax, I do not care how it is spent, all I want is the evidence Mr Blair promised me."
A lawyer for Blair, Jeremy Johnson, said: "The prime minister is unable to give any evidence that could possibly be relevant to the issues in dispute between the parties."
Judge John Freeman said that he had no power to compel the prime minister to supply the requested evidence.
"You may feel you have cause to be aggrieved with Mr Blair, you may feel he should supply you with the information he said he would, but this is something the court cannot interfere with in any way, the court cannot direct the prime minister to supply you with this information," Freeman said.
Freeman ordered Blackburn to pay the unpaid taxes plus interest and court fees.