The 7th U.S. Circuit Court of Appeals ruled Friday that police properly obtained Dassey's confession and he should remain behind bars. The judges were sharply divided, voting 4 to 3 that Dassey's confession wasn't coerced.
His attorneys, Laura Nirider and Steven Drizin, say they'll ask the U.S. Supreme Court to review the case. They say the 7th Circuit judges ignored the fundamental idea that false confessions often result when children or the mentally vulnerable are interrogated.
Dassey was sentenced to life in prison in 2007 after he told detectives he helped his uncle, Steven Avery, rape and kill photographer Teresa Halbach.
"The state courts' finding that Dassey's confession was voluntary was not beyond fair debate, but we conclude it was reasonable," their 39-page ruling said.
But Judge Ilana Diamond Rovner strongly disagreed.
"His confession was not voluntary and his conviction should not stand, and yet an impaired teenager has been sentenced to life in prison," she wrote in her dissent. "I view this as a profound miscarriage of justice."
In her dissent, Chief Judge Diane P. Wood added: "Without this involuntary and highly unreliable confession, the case against Dassey was almost nonexistent."
A federal magistrate judge overturned Dassey's conviction last year, ruling that detectives took advantage of Dassey's youth -- he was 16 at the time -- and learning disabilities to coerce his confession. A three-judge panel from the 7th Circuit upheld the magistrate's ruling in June. But the state asked for a review by the full 7th Circuit -- leading to Friday's decision.
Dassey's attorneys, Laura Nirider and Robert Drizin, said they were "profoundly disappointed" and would seek relief from the U.S. Supreme Court.
"Today's ruling contravenes a fundamental and time-honored position of the United States Supreme Court: interrogation tactics that may not be coercive when applied to adults are coercive when applied to children and the mentally impaired," they said in a statement.
State attorneys asked the full 7th Circuit to review the case, arguing the ruling called long-accepted police interrogation tactics into question. The appellate court rarely grants such reviews but opted to take Dassey's case in August without comment on the merits.
Dassey has remained in prison while the state appeals.
Both Avery and Dassey contend police framed them because they wanted revenge against Avery for filing a lawsuit against Manitowoc County over wrongful imprisonment for a sexual assault he didn't commit.
A federal judge overturned Dassey's conviction in 2016, ruling that investigators coerced his confession. A three-judge panel from the 7th U.S. Circuit Court of Appeals agreed, but the state asked for a review by the full court that led to Friday's decision.
The confession was one of the focal points analyzed in the Netflix Documentary “Making a Murderer,” which followed the details of both Dassey’s and Avery’s cases.