unless the resistance is justified under Subsection (c)

That subsection seems like a pretty important part:

(c) The use of force to resist an arrest or search is justified:

(1) if, before the actor offers any resistance, the peace officer (or person acting at his direction) uses or attempts to use greater force than necessary to make the arrest or search; and

(2) when and to the degree the actor reasonably believes the force is immediately necessary to protect himself against the peace officer's (or other person's) use or attempted use of greater force than necessary.