CONCORD, N.H. — A New Hampshire man convicted of wiretapping for recording his conversations with Manchester police and school officials thought he had a right to record public officials, his attorney told state Supreme Court justices Wednesday.

CopBlock.org founder Adam Mueller should get a new trial because the trial judge did not tell jurors they could acquit him if they found that he believed what he was doing was legal, attorney Brandon Ross said.

Assistant Attorney General Lisa Wolford countered that the outcome would have been the same and noted that Mueller told jurors he disagreed with the law and urged them to ignore it and find him not guilty.

Mueller — who was convicted last year on three counts of felony wiretapping and served three months behind bars — did not attend the hearing.

Ross stunned the justices by dropping his challenge that misdemeanor wiretapping was the more proper verdict, saying the state’s arguments on that point were compelling. Chief Justice Linda Dalianis told him they seldom hear such a concession.

Ross focused instead on the trial judge’s instruction that the jury had to find he “purposely” violated the law. The standard set down in the wiretapping statute is “willfully” violated the law, which Ross cast as a higher standard. He said the state had to prove he knew his conduct was illegal.

Wolford emphasized that “willful” also includes reckless disregard of the law.

Mueller acknowledged during his trial that he did not state his affiliation with Cop.Block.org — an organization that claims to police the police — when he called a Manchester police captain and two school officials in 2011 about a police officer allegedly roughing up a student at a Manchester high school. He then posted the conversations online.

Justice Carol Ann Conboy asked Wolford whether the judge’s failure to give the proper instruction on mental state tainted the integrity of the trial.

“Not really,” Wolford replied. “The defendant’s defense was jury nullification,” when jurors acquit a defendant they believe is guilty.

When asked about Mueller’s jury nullification request, Ross told the justices he was sorry Mueller used that term and rued that Mueller had elected to represent himself at trial.

After court, Ross said the outcome would have been radically different had Mueller hired a lawyer.

“He would not have gone to jail and he would not have been convicted, of that I’m certain,” Ross said. “Now it’s an uphill battle.”

At the start of his August 2012 trial Mueller was behind bars, serving a 60-day sentence for resisting arrest after writing messages on the police department’s walls in chalk.