Aldon Smith is in trouble with the law once again ... TMZ Sports has learned the NFL star was arrested on Monday and booked on a felony charge of DUI causing injury.
Details surrounding the arrest are unclear -- we're working on it -- but records show Smith was booked into a Northern California jail at 7:38 p.m. on Monday night.
The records show Smith's bail has been set at $50,000. Smith is still in custody.
The 32-year-old pass rusher is due in court for a hearing on the matter on Wednesday, according to the records.