There surely were fist pumps among white-collar defense lawyers when the U.S. Supreme Court—overturning bribery convictions of former Virginia Gov. Robert McDonnell—narrowed the scope of official conduct that qualifies as an element of bribery.

But how directly the decision may impact any particular political corruption case, including that of U.S. Sen. Robert Menendez, D-New Jersey, is unclear. Criminal lawyers offer differing opinions on the nature and degree of its effect.