According to TMZ, Willis was originally pulled over last Friday in Lake County Florida due to a faulty headlight.
Records state that officers could immediately smell marijuana coming from the vehicle and proceeded to search it. Upon further inspection, a grinder and several baggies of LSD were discovered.
Willis was reportedly arrested for felony possession of a controlled substance, though he claimed the LSD did not belong to him. He is due to appear in court next month.
Willis featured in three seasons of American Idol, reaching the quarterfinals in season 12.