Cal. Ed. Code § 68124
The trustees may enter into agreements with public colleges and universities in other states whereby qualified students from the California State University may attend the other college or university without payment of any tuition fee charged by that institution to persons who are nonresidents of the state in which it is situate, and students from that institution may attend the California State University without payment of the nonresident tuition established pursuant to Section 89705. No nonresident tuition shall be charged of students attending a campus of the California State University pursuant to an agreement entered into under this section. During any year, however, the number of students attending the California State University from a particular public college or university in another state, pursuant to the agreement, shall not exceed the number of the California State University students attending the institution under that agreement.
Ca. Educ. Code § 68124