California Code, Probate Code - PROB § 12523

(a) Except as provided in subdivision (b), if a will of a nondomiciliary decedent was admitted to probate, or established or proved, in accordance with the laws of a foreign nation, the court shall admit the will to probate in this state, and may not permit a contest or revocation of probate, if it appears from the order admitting the will to probate in the foreign nation, or otherwise appears, that all of the following conditions are satisfied:

(b) The court may refuse to admit the will, even though it is shown to satisfy the conditions provided in subdivision (a), where the order admitting the will was made under a judicial system that does not provide impartial tribunals or procedures compatible with the requirements of due process of law.