The Unit -- 'Jersey Shore' Star Pleads NOT GUILTY in Drug Case

The Unit claims there's no way in hell he was in possession of a powerful horse tranquilizer when he was arrested in Seaside Heights last year ... and just pled NOT GUILTY to the charge in a NJ court.

The "Jersey Shore" star -- real name John Manfre -- was arrested in Seaside Heights back in July for possession of a controlled substance ... later determined to be Ketamine, often used as a horse tranq.

After the hearing, Unit's lawyer, Raymond Raya, told us, "There were some issues regarding my client's constitutional rights."

The lawyer added, "We entered the not guilty plea NOT because that's the normal thing to do ... we actually entered the not guilty plea because we believe that based on those issues, John is not guilty."