Pass interference or not? No one in the NFL seems to know.

Denver Broncos head coach Vic Fangio gets bad news on a challenge on the side lines as his team falls to the Indianapolis Colts 15-13 at Lucas Oil Stadium in Indianapolis, Indiana on Oct. 27, 2019. By Ben Shpigel, The New York Times

To the chagrin of dumbfounded coaches and confused teams, perplexed broadcast crews and enraged fans, every week across the NFL’s vast empire one player interferes with another before a pass arrives — and goes unpunished for it.

In these moments, when yellow penalty flags remain lodged in officials’ pockets, aggrieved coaches weigh emotion against reason: Do they challenge the non-call, hoping that by sheer luck it will be overruled by the new instant replay…