The mistake, made when the Harris County district attorney's office extended the grand jury's term in November, invalidated all indictments issued after that point, District Judge Jim Wallace ruled. That includes last week's tampering-with-evidence charge against Justice David Medina, and an arson charge against his wife, in connection with a fire at their home in June.

District Attorney Chuck Rosenthal had quickly dropped the charges, saying there was insufficient evidence. Angry grand jurors said the move was politically motivated, and their foreman, Robert Ryan, said he had planned to reconvene the panel Wednesday to issue another indictment.

Those plans were scuttled by Wallace's ruling, said Ryan, who has served on five grand juries.

Ryan said he and several other grand jurors were outraged by the judge's decision over what he described as a "boilerplate" order routinely issued by the district attorney's office to extend grand jury terms.

"That just shows you the sheer incompetence of the district attorney's office of Harris County, Texas," Ryan said.

Prosecutors have said they are continuing to investigate the June 28 fire that destroyed the Medinas' home, damaged two other houses and caused nearly $1 million in damage in the Houston suburb of Spring. But the couple's attorney Terry Yates expressed hope that the case was over.

"It's been a roller coaster for them. Obviously, they're very pleased," Yates said. "We hope this is a final chapter in this case and that it effectively ends the prosecution of David Medina."

The fire marshal's office has said the fire was not electrical or accidental. A dog detected an accelerant at the scene.

Investigators became suspicious after discovering a mortgage company sued in June 2006 to foreclose on the $300,000 home. The lawsuit, filed after the family missed payments for five months, was settled in December 2006.

Yates has acknowledged the family had financial problems. They owed nearly $1,900 in fees to a homeowners association and let the insurance policy on the house lapse, meaning losses from the fire were not covered.

Medina was appointed by the governor to the state's highest civil court in 2004 and elected to a full term two years later. He and the district attorney are Republicans.

Rosenthal dropped out of his re-election campaign but has refused calls for his resignation after the embarrassing release of dozens of pornographic, racist and political e-mails on his office computer.