The former "Empire" actor is heading to trial next month -- this after a Cook County judge shot down JS's final attempt to have the criminal case against him tossed ... setting the stage for Jussie to face a jury of his peers over the 2019 incident.

Smollett's attorney tried convincing the court that his client's rights were being violated, seeing how the guy had already forfeited his $10,000 bond and done community service ... which served as the terms he struck with Cook County prosecutors to have the charges dismissed.

Per reports, the attorney noted Smollett had held up his end of the bargain, saying ... "A deal is a deal. That's ancient principle." Not so, according to the judge -- who noted a new set of circumstances arose when a special prosecutor reopened the case ... and charged Jussie anew.

Because of that, the judge said he wouldn't tamper with the new case. As you know, Jussie faces charges of disorderly conduct for allegedly lying in the police reports about what happened to him.

As we've reported ... Jussie claimed he was jumped by two white males wearing red MAGA hats, who hurled racist and homophobic epithets at him ... poured bleach on him ... and then threw a noose around his neck. Jussie kept that noose on until cops arrived and got his story -- an interaction that their body cameras captured upon entering his Chicago apartment.

As the initial investigation unfolded, police say they found that his so-called attackers weren't white at all -- they were two Black men, the Osundairo brothers, whom knew Jussie well from working on "Empire" ... and who confessed to staging the whole thing at Jussie's behest.

There's footage of the guys buying the supplies they used that night ... and even walking past Jussie at one point on the streets. The brothers claim Jussie paid them to set up the entire attack ... something he's denied entirely at every turn, defiant to prove his innocence.