system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can a layperson tell whether a police/FBI/government badge or ID is authentic?

I've been reading the Jack Reacher novels recently (great stuff, btw), and badges or ID are shoved into people's faces about every 3rd page. It occurred to me that if that ever happened to me, I'd have no way to know whether the person was lying or not. As a layman in this area, I have literally no basis for which I could judge this sort of thing. 

So, I'm wondering if there are certain things that are well known about badges or IDs that would help the average person.
gpt
Unless it's something obviously fake like a Colgate Cavity Patrol badge there's no good way to tell. There's no standard police badge across the United States. Even if there were, old ones could get sold and authentic-looking replicas could be made. 

If you have doubts about whether someone is a police officer or not you can either call 911 to verify that an officer is who they say they are or you can ask to look at their department issued ID card.