Former federal prosecutors blame juror skepticism and the new, more permissive legal definition of bribery for the stunning mistrials Thursday when two federal juries were declared hung in high-profile public corruption cases.

The mistrials in the cases of Sen. Robert Menendez (D-NJ) and former corrections union leader Norman Seabrook came within two hours of each other.

“I think the questions that some of us are asking is whether it’s the courts narrowing the scope of what constitutes public corruption,” says former Manhattan prosecutor Randall W. Jackson.

Last year, in reversing the bribery conviction of Virginia’s former Gov. Bob McDonnell, a Republican, the US Supreme Court narrowed the definition of bribery, saying the government must demonstrate a specific quid-pro-quo agreement between briber and bribee.

That decision also led to the July overturning of the corruption conviction of former state Assembly Speaker Sheldon Silver.

“It’s becoming very difficult to get convictions in these public corruption cases,” said former Brooklyn federal prosecutor Brad Simon, who as a defense attorney got Alan Hevesi cleared of state corruption charges.

“There’s a general skepticism and cynicism in public life today which carries over to jury trials,” he said.