I subscribe to a "Latin word of the day" email, which sends me a random vocabulary word and an example sentence every day. Last night's email had this:
pecco, to sin.
Nemo accusator caret culpa; omnes peccavimus.
The translation seems to be "no accuser is free from guilt; we have all sinned".
But I'm confused by the nemo at the beginning. I'm used to nemo being a noun; if I were translating this sentence into Latin, I would have used nullus here instead.
Is it correct to use nemo as an adjective like this? If so, what's the difference in meaning—that is, what would be different if I used nullus instead here?