Mark Geragos -- who repped Jussie during his criminal trial when he was still in the hot seat in Chicago -- filed legal docs asking a judge to toss the Osundairo Bros.' defamation lawsuit against him, one of his colleagues and his firm, which they filed in April.

One of the main quotes the brothers were suing over in their initial complaint was something they alleged attorney Tina Glandian -- another one of Smollett's attorneys -- said to the media that implied they were part of "illegal" Nigerian steroid trafficking.

The quote the Osundairos attributed to Glandian in their lawsuit read, "platform ... is all about being steroid-free ... Their whole thing is, you know, all-natural bodybuilding. It's ridiculous."

Welp, Geragos points out in his court filing that Ms. Glandian never said that at all -- in fact, it was their attorney, Gloria Schmidt, who said that to the Chicago Tribune in early April ... word-for-word. That alone, Geragos argues is enough grounds for dismissal -- but there's more.

Geragos and co. say that the brothers also paraphrased something they claimed Geragos said on a podcast he does with comic Adam Carolla, alleging the celeb attorney dragged their reps through the mud by indicating they'd attacked Jussie, committed perjury and conspired to make false statements to clear their names.

Geragos submitted transcripts of his podcast during the time of the criminal legal proceedings, and he notes ... he never said the brothers' names, nor did he say or indicate what they attributed to him. Another example Geragos cites for nixing this thing.

Long story short ... Jussie's attorneys say the brothers can't get their quotes straight, and by falsely attributing statements to Geragos and co. ... the suit should be axed, and the Brothers should also be punished with sanctions for allegedly lying to the court.