Constitutional Amendments
The University of California, Davis adopted STV/Choice Voting in 2003. The following is a link to the background of their decision to implement STV for their elections as well as the necessary Constitutional Amendments that were subsequently voted on in a referendumConstitutional wording for UC, Davis:
http://www.ucdgreens.org/cva/cvatext.shtml
You can look at the entire website as for complete details on their adoption of Choice Voting for their Student Senate*.
*Note: this website was designed by the UC, Davis Green Party and is currently operated by them. It has all the relevant information about Choice Voting at UC, Davis as well as information on the party itself.