Isn't this all about you threatening to stomp a drug dealer's teeth down his throat if he didn't stop giving your ex coke?
But to answer your question, yes.
If we're talking about the use of non-deadly force in self-defense...
"A non-aggressor is justified in using force upon another if he reasonably believes that such force is necessary to protect himself from IMMINENT use of unlawful force by the other person. The use of force must not be excessive in relation to the harm threatened."
Straight out of my crim law outline, so it must be reliable.