"I feel deceived by Mr. Mesereau and I am considering ... sanctions of some sort against Mr. Mesereau," Superior Court Judge Rodney S. Melville said in a hearing before Geragos resumed testifying.
Originally the defense gave Geragos a complete waiver of attorney-client privilege, reports CBS News Correspondent Steve Futterman. Then, in the middle of testimony, Jackson's attorneys changed it to a limited waiver.
The prosecution and the judge were surprised by the limitation, and at the time Mesereau apologized, saying he had not thought the period after arrest was relevant.
Defense attorney Robert Sanger argued Friday that he had given a copy of the waiver to the district attorney and the judge's clerk, but it apparently hadn't been read.
The judge said that was not relevant because he considered Mesereau to have misrepresented the waiver in his statements in open court.
Prosecutors argued that Geragos should be required to testify about the period after the arrest because of the misrepresentation, but the judge ruled that Geragos would only have to testify about the period allowed by the waiver.
The judge said he could have stricken Geragos' testimony from the record but didn't think that was viable because jurors had already heard it and were likely to remember it during deliberations.
Most court observers expect the sanctions to include a fine.
"Whatever the judge decides to do with Mesereau, it won't make a bit of difference to the ultimate outcome of the case against Jackson. The only thing it will do, and already has done, is make the judge a little more wary of what the defense says in court," says CBSNews.com Legal Analyst Andrew Cohen.
In a victory for Michael Jackson's defense, jurors in his child molestation case were allowed Thursday to see a video tour of the singer's Neverland ranch that a prosecutor condemned as propaganda.
Jurors saw idyllic scenes of amusement park rides, cheerful workers, zoo animals, blooming flowers and statues of boys and girls at play.