The Assault

This was originally meant to be the series finale. There's a birthday party, celebrating a job well done, and then ends with Matlock (Griffith) looking over an empty court room, as though he's saying goodbye. The show stopped airing in its regular time slot, but resumed its run later that spring, by airing the remaining two episodes (that were in the can) in April and May of 1995, respectively.

When the police detective and a uniformed officer visit Johnson at his apartment the uniformed officer casually goes to the closet and begins searching it, discovering a blood soaked shirt. Since the detective did not have/produce a search warrant when they arrived, the bloody shirt would have been illegally obtained evidence. Every lawyer, including Ben, would know that and would have had the evidence thrown out. Without the bloody shirt the case should never have gone to trial.

The officers were invited into the apartment. The shirt was in plain sight at the bottom of the closet. A case could be made that the seizure of the shirt met the "plain view" doctrine and therefore would likely not be thrown out in court.