There are signs key portions of the corruption case against former U.S. Rep. Aaron Schock may be at risk of unraveling.

The U.S. 7th Circuit Court of Appeals in Chicago is currently considering a question on which the outcome of the Illinois Republican's case may rest. It's whether prosecutors based charges on ambiguous House rules in violation of the U.S. Constitution.

Schock has long argued federal prosecutors did just that. He recently asked the 7th Circuit seeking to dismiss all charges for that reason.

But the constitutional arguments have gained support. A former prosecutor in the Department of Justice, Daniel Petalas, says there's "a genuine dispute" over the constitutionality of the charges.

Prosecutors have said House rules weren't ambiguous, and that half the charges aren't even based on House rules.