A Massachusetts man sentenced to 17 1/2 years in prison for supporting al-Qaeda is challenging his conviction based on the First Amendment. He claims “his unpopular thoughts and expressions [won] a conviction that the facts could not.”

Tarek Mehanna fired his opening appellate salvo against the government at the U.S. Court of Appeals for the First Circuit with a brief filed on December 18.

Mehanna was a 27-year-old pharmacist living with his parents in the upscale Boston suburb of Sudbury, Mass., when he was arrested in November 2008. He was indicted on terrorism- and conspiracy-related charges and for providing false information to the government.

The government claimed he participated in a conspiracy to support al-Qaeda from 2001 until 2010 by providing personnel, advice and assistance.

His actions included traveling to Yemen in 2004 to seek terrorist training. Also, in early 2006, he created, translated or took credit for translating text, videos and media that encouraged others to participate in violent jihad.

During his trial in the District of Massachusetts, Mehanna’s lawyers emphasized that he was teenager when the conspiracy began and that his web postings became more moderate over time.

Mehanna was convicted last December and sentenced in April. He was defiant at this sentencing hearing. Judge George O’Toole Jr. cleared the court for 20 minutes after Mehanna shouted, “You’re a liar! Sit down!” at a prosecutor.

Mehanna’s brief states that “a jury was directed to disregard the First Amendment” and that the jurors were “buried in inflammatory, prejudicial, and irrelevant evidence” that included violent videos and images of the September 11, 2011, terrorist attacks.

It also alleges that the trial court engaged in a “profound misapplication of conspiracy law and rules in speech cases.”

Specifically, the briefs states, “[T]he court permitted the government to expand the theory of criminal agreement from a Yemen trip in which Mehanna participated, to distinct enterprises in which he did not.”

Mehanna in his brief also attacked the government’s theory that his speech was the same as providing material support: “[T]he government conceded that Mehanna did not translate at al Qa’ida’s direction and offered no evidence that he did so at its request, nor that Mehanna ever met or communicated with anyone from al Qa’ida about undertaking this work.”

The U.S. Attorney’s Office for the District of Massachusetts declined to comment, said office spokeswoman Christina DiIorio-Sterling.

Sabin Willett, a Boston partner at Bingham McCutchen and Mehanna’s lead counsel on the appeal, said he’d “let the brief speak for itself.”

J.W. Carney Jr. of Boston’s Carney & Bassil, one of Mehanna’s lawyers and his co-counsel on the appeal, referred questions to Willett.

Sheri Qualters can be contacted at squalters@alm.com.