California Code, Civil Code - CIV § 1646.5

Notwithstanding Section 1646, the parties to any contract, agreement, or undertaking, contingent or otherwise, relating to a transaction involving in the aggregate not less than two hundred fifty thousand dollars ($250,000), including a transaction otherwise covered by subdivision (a) of Section 1301 of the Commercial Code, may agree that the law of this state shall govern their rights and duties in whole or in part, whether or not the contract, agreement, or undertaking or transaction bears a reasonable relation to this state. This section does not apply to any contract, agreement, or undertaking (a) for labor or personal services, (b) relating to any transaction primarily for personal, family, or household purposes, or (c) to the extent provided to the contrary in subdivision (c) of Section 1301 of the Commercial Code.

This section applies to contracts, agreements, and undertakings entered into before, on, or after its effective date;  it shall be fully retroactive. Contracts, agreements, and undertakings selecting California law entered into before the effective date of this section shall be valid, enforceable, and effective as if this section had been in effect on the date they were entered into;  and actions and proceedings commencing in a court of this state before the effective date of this section may be maintained as if this section were in effect on the date they were commenced.