A lot of hyperbole has been written about what "ought" to be done with regards to reforming, or lowering the cost of, public pensions. However, that’s very different from what "can" be done, legally.
California case law and the California and U.S. constitutions have enshrined the concept of legally binding contracts. Under that concept, once a public entity enters into a contract with employees, it cannot rewrite that contract without the agreement of the employee. Therefore, according to current law, CalSTRS core pension benefits (retirement, disability and survivor benefits) are guaranteed by both the U.S. and California constitutions.