If we are to be technically precise, a California marriage dissolution or legal separation can be only be realized on grounds of irreconcilable differences or incurable insanity.
More particularly, irreconcilable differences must have arisen which have led to the irremediable breakdown of the marriage. In other words, the court has to determine that substantial reasons exist for not continuing the marriage. The notion of irreconcilable differences is broad by design. Specific categories of abhorrent behavior have been eliminated. For example, a divorcing spouse does not have to prove that the other was unfaithful, or abusive, etc. This “no fault” system eliminates specific acts of misconduct, and instead reduces the process to in inquiry whether the marriage has deteriorated beyond the point of being saved. In practice the courts usually construe no fault as a low threshold, ordinarily being satisfied with either spouse’s belief that the marriage should end.
Because California is a no fault state, there is also little chance of blocking a divorce. In fact, when the court finds that irreconcilable differences have led to the irremediable breakdown of the marriage, the court must dissolve the marriage.
Other than irreconcilable difference, a marriage can be dissolved by the California court if it is determined that one of the spouses suffers from incurable insanity. In other words, if one spouse is proven to be incurably insane at the time that the divorce case is filed with the court, then the marriage can be dissolved. Appreciate however that it will be more expensive and complicated to dissolve a marriage based on incurable insanity. Ordinarily expert medical testimony will be required, as will an actual court trial.