What are the penalties for stabbing someone non fatally for self defense in California?

Depending upon the underlying facts of the case, a California prosecutor has the discretion to charge you with carrying an illegal knife and/or carrying a concealed weapon, as well as assault, assault with a deadly weapon or attempted murder.  For this combination of possible offenses, the penalties could range from a misdemeanor fine to a felony sentence with a possible range of several months to a life sentence depending upon your history of prior felony convictions.

In California, “self-defense” is permitted when there is a reasonable belief that one is in danger of immediate bodily injury.  The right to self-defense lasts only as long as the real or apparent threatened danger exists, and a person acting in self-defense is normally allowed to use only as much force as appears reasonably necessary to repel the attack.  In situations involving mutual combat, to prevail upon a self-defense claim one must prove that s/he affirmatively showed the opponent that s/he was discontinuing the fight, and that s/he gave the opponent time to realize this and stop fighting.

You should immediately retain or seek court-appointment of a qualified criminal defense attorney.  S/he will need to independently investigate all relevant facts; it is best if this investigation is well underway before the final charging decision has been made.  In these situations, the critical facts go beyond the specifics of the confrontation that ended in the stabbing.  For example, both the prosecution and your attorney will need to investigate your prior relationship with the victim, your and the victim’s history of aggression and/or violence towards others, and your and the victim’s propensity to carry and/or use weapons.