Code of Civil Procedure § 748
CHAPTER 3. Actions for the Recovery of Real Property, and Other Provisions Relating to Actions Concerning Real Property
In actions respecting mining claims, proof must be admitted of the customs, usages, or regulations established and in force at the bar or diggings embracing such claim; and such customs, usages, or regulations, when not in conflict with the laws of this State, must govern the decision of the action.