Legal Question in Business Law in California

Possibly, but there's some significant doubt in my mind. I would prefer that you discussed a termination by mutual agreement, to see if this is possible. Here are two references on the subject. The first is a quote from a legal Web site I found on Google:

#1: "One party to a contract can rescind it because of substantial nonperformance or breach by the other party. The party who knowingly and willfully fails to perform cannot complain that the other party to the contract has injured him or her by terminating the contract. The right to rescind does not arise from every breach but is permitted only when the breach is so substantial and fundamental that it defeats the objective of the parties in making the agreement. The breach must pertain to the essence of the contract. The act must be an unqualified refusal by the other party to perform and should amount to a decision not to be bound by the contract in the future. A party to a contract who is in default cannot, however, rescind because of a breach by the other party."

Your publisher's conduct may rise the the level (of breach) required per the quoted material, but without thorough investigation I'd be cautious.

Reference #2 is a quotation from California's Civil Code, section 1689(b)(2): "A party to a contract may rescind the contract in the following cases: ......... (2) If the consideration for the obligations of the rescinding party fails, in whole or in part, through the fault of the party as to whom he rescinds."

If you contract for X, and the other party delivers 0.7X, or delivers X months late, this is probably a partial failure of consideration, and warrants rescission. However, the breach by the party against whom rescission is taken must be material and substantial, not trivial.

If you terminate (rescind) the contract, there is always a possibility that the publisher may take you to court, and if it does, there is a possibility that it would win. I cannot tell you the odds of either happening, Further, if the publisher is in arrears in paying you, I cannot say whether they will ever complete the payment of funds they owe at the point they get your termination (rescission) notice.