Kenneth Walker filed a civil lawsuit Tuesday, asking the judge for a declaration of immunity from prosecution in the criminal case for firing a single "warning shot" after cops rammed the door to enter Taylor's apartment in the middle of the night back in March while executing a search warrant.

As you know ... police claim Walker's shot struck Sgt. Jonathan Mattingly in the femoral artery in his thigh, but his legal team refutes that.

Walker's lawyers say evidence indicates that police may have shot Mattingly as they were "firing wildly from various angles."

According to the lawsuit ... Walker was interrogated by police after the shootings and was then wrongfully and illegally arrested, detained, charged and prosecuted.

Walker now wants to avail himself of Kentucky’s stand your ground law, which he claims operates to prevent law enforcement from prosecuting him after he fired the shot in self-defense. In other words, it seems the lawyer is saying Walker had a right to fire a shot under the stand your ground law, so he would therefore be immune from criminal prosecution.

According to the docs, he's specifically concerned about being hit with an attempted murder charge that was previously dropped without prejudice.

Taylor's boyfriend is also seeking damages for assault, battery, false arrest and imprisonment, malicious prosecution, abuse of process and negligence stemming from the incident.

As we've reported ... none of the officers involved in the raid and shooting of Taylor have been arrested, though one cop -- Brett Hankison -- has been fired.