James Ward of WireGhost Security told the court he was an expert in computer network security, but the prosecution questioned his qualifications to testify about Cooper's computers as a forensics expert.
Cooper is charged with murdering his wife Nancy in 2008. Her body was found dumped beside a drainage pond in an unfinished Cary subdivision not far from her home. An autopsy showed she'd been strangled.
The issue before Superior Court Judge Paul Gessner Tuesday was the treatment of Cooper's computers while in police custody. The defense has charged that they could have been tampered with.
Proving tampering would be a significant blow to expert testimony already before the jury that an examination of one of Cooper's computers showed a search was made for the location where Nancy's body was found using Google maps some 12 hours before she was reported missing.
Arguing before Gessner Tuesday, the prosecution said Ward lacked the proper education and experience to say there was evidence of computer tampering.
"He has a home lab. He borrowed his tools from Cisco. He doesn't know what software he used," said prosecutor Boz Zellinger.
Zellinger said the prosecution and defense should be held to the same standards on expert witnesses, and Ward falls short.
"I would be laughed out of this building," said Zellinger.
Gessner ruled that Ward could testify about network security, but he could not testify about the FBI reports on Cooper's computers.
"I don't believe he is properly qualified as a forensics analyst," said Gessner.
While Special Agent Greg Johnson was on the stand, the defense asked that he run a demonstration of a Web search. The prosecution objected and Gessner sustained. That ruling prompted defense attorney Howard Kurtz to ask for a mistrial - saying Gessner's rulings have shown a pattern of bias that are "outside the bounds of jurisprudence."
Gessner denied Kurtz's request.
Debate over Ward's qualifications took all of the morning without the jury in the courtroom.
Prosecutors rested their case Monday. They allege Brad killed Nancy because he was angry she planned to divorce him and move with their two daughters to Canada.
Cooper's lawyers say he is innocent and have characterized the investigation by the Cary Police Department as inept. They say detectives focused on Cooper from the beginning of their investigation and never looked at other suspects.