No, but I'm having a hard time finding a reference now :/ You may be able to argue malicious prosecution, in which that may be a piece of evidence. The bar for MP is quite high though.
Another far-fetched strategy would be to argue that, because of the government's inconsistency about how the law is applied, the law itself might be unconstitutionally vague.[0] This is not legal advice, though.
Defendants certainly argue that a particular prosecution is selective enforcement and will refer to DOJ policies.
‘Making an example of someone’ that they happen to catch (and being terrible at catching most people) is still perfectly fine however. So good luck with that.
My understanding is that in the US "singling out" specific criminals is perfectly OK for the prosecution to do (well, legally speaking, I'm not saying it's ethical or won't get them in trouble with voters).
(Again, given you aren't singling them out because of a protected class like race, sex, etc)
Like pointed out in a sibling thread though, essentially impossible to prove, let alone get anyone to care about, and useless as a defense unless someone is being stupidly blatant about it.