Evan Greebel, the former partner at Katten Muchin Rosenman and Kaye Scholer convicted of fraud conspiracy for helping Martin Shkreli rip off his company Retrophin, had his conviction affirmed by a federal appeals court Wednesday.

In a three-page summary order, the U.S. Court of Appeals for the Second Circuit said Greebel was mistaken in his arguments that the jury was given bad instructions and that one of his expert witnesses should have been allowed to testify.

The decision could make it difficult for Greebel, who was suspended from the bar, to practice law again. He was given an 18-month prison sentence after his December 2017 conviction. He is living in a halfway house, where prisoners can reintegrate into society while finishing their sentences, after being transferred on Sept. 27 from the federal prison in Otisville, according to the Bureau of Prisons.

In the Wednesday decision, the appellate panel, composed of Judges Rosemary Pooler and Joseph Bianco of the U.S. Court of Appeals for the Second Circuit and Judge Jennifer Choe-Groves of the U.S. Court of International Trade, sided with Greebel on the standard of review to apply. But the panel said the challenged decisions by U.S. District Judge Kiyo Matsumoto of the Eastern District of New York were correct.

Matsumoto's decisions were consistent with Second Circuit case law, and on two points, even if they hadn't been, Greebel hadn't shown how he was harmed by them, the appeals court ruled.

"Under any articulation of an attorney's duty of disclosure, Greebel would need to disclose that Retrophin was committed to pay or was paying millions of dollars to investors defrauded by its CEO [Shkreli]," the court said.

Greebel's jury instruction argument had received some support from a group of legal ethics and professional responsibility experts who filed an amicus brief during his appeal.

It wasn't immediately clear whether Greebel would appeal his case further. The Second Circuit is known for only rarely granting requests for rehearing. Kannon Shanmugam, a partner at Paul, Weiss, Rifkind, Wharton & Garrison who represents Greebel, declined to comment. John Williams, Michael Mestitz and Meng Jia Yang of Williams & Connolly also worked on Greebel's appeal.

The government was represented by a team from the U.S. Attorney's Office for the Eastern District of New York, including Alixandra Smith, David James, David Pitluck and David Kessler. A spokesman for the office declined to comment.