'RHOSLC' Star Mary Cosby's Son Arrested for Assault, Trespassing

Mary Cosby's son Robert Jr. has found himself in hot water with the law again ... we've learned he's been arrested for a number of alleged crimes, including assault and trespassing.

According to an arrest report, obtained by TMZ ... "The Real Housewives of Salt Lake City" star's only child was arrested just outside Salt Lake City, UT Saturday for failure to stop at the command of law enforcement, criminal trespassing, assault, and 3 alleged violations of a court order.

Per the report, local police responded to a domestic violence call after Robert Jr. allegedly tried to break into his father-in-law's home via a dog door and assaulted someone on the front lawn.

Robert Jr. allegedly failed to get on the ground when ordered to do so by the responding police officer ... before eventually complying and being taken into custody.

Bail has been set at $5,000.

This is Robert Jr.'s latest set of legal troubles ... he was previously arrested in 2022 for a DUI, where cops say he didn't have a license and disobeyed traffic laws. He ended up pleading guilty to the DUI ... resulting in the other charges being dropped.

However, the saga didn't stop there, with Robert Jr. finding himself back in court after he allegedly failed to prove he completed a court-ordered rehab stay. Though Mary previously said on the 'RHOSLC' reunion that Robert Jr. did attend a rehabilitation program and was doing "good."

Remember, Mary opened up about her son's struggles on the Bravo series, having a viral heart-to-heart with her son in Season 5 ... where she begged her son to be honest with her about his issues.

However, during Wednesday's appearance on SiriusXM’s "Reality Checked" radio show, she hinted that Robert Jr. was struggling with substance issues again ... noting her husband, Robert Sr., was "devastated" by their son's battle.

She added ... "I can just only push him, encourage him and love him. And that's what I'm doing. That's kind of where we are ... But he's still on that road and it's a hardcore road."