WASHINGTON — The judge declared a mistrial today in baseball star Roger Clemens’ perjury trial after prosecutors showed to jurors evidence that he had ruled would be out of bounds in the case.

U.S. District Judge Reggie Walton said Clemens could not be assured a fair trial after prosecutors showed jurors evidence against his orders in the second day of testimony.

Walton scheduled a Sept. 2 hearing to determine whether to hold a new trial. He told jurors he was sorry to have wasted their time and spent so much taxpayer money, only to call off the case.

“There are rules that we play by and those rules are designed to make sure both sides receive a fair trial,” Walton told the jury, saying such ground rules are critically important when a person’s liberty is at stake.

He said that because prosecutors broke his rules, “the ability with Mr. Clemens with this jury to get a fair trial with this jury would be very difficult if not impossible.”

Prosecutors suggested the problem could be fixed with an instruction to the jury to disregard the evidence, but Walton seemed skeptical. He said he could never know what impact the evidence would have during the jury’s deliberations “when we’ve got a man’s liberty at interest.”

“I don’t see how I un-ring the bell,” he said.

By The Associated Press