For federal prosecutors, the ruling by the U.S. Second Circuit Court of Appeals to throw out the conviction of former New York state Assembly Speaker Sheldon Silver on Thursday highlights the challenges of winning public corruption cases in the post-McDonnell era.

The U.S. Supreme Court's decision in McDonnell v. United States, No. 15-474, which was handed down after Silver's conviction in November 2015 of four counts of theft of honest services, two counts of Hobbs Act extortion and money laundering, narrowed the definition of what can be considered an “official act” under the federal bribery statute.

The Second Circuit's decision to overturn Silver's conviction—which centered on an overbroad jury instruction from Southern District Judge Valerie Caproni—may also shake up the prosecution of former state Senate Majority Leader Dean Skelos, who is awaiting a ruling from the federal appeals court in his corruption case.