Nine California public school students are suing the state to abolish its laws on teacher tenure, seniority and other protections that the plaintiffs say keep bad educators in the classroom. The trial that begins Monday in Los Angeles Superior Court is the latest battle in a nationwide trend. The lawsuit's lead attorney Theodore J. Boutrous says Los Angeles Unified School District Supt. John Deasy will be among the witnesses called by the plaintiffs. Dozens of states have moved in recent years to either abolish or toughen the standards around giving teachers permanent employment protection and seniority-based preferences during layoffs. Unions say eliminating such laws is erasing a vital support system for a profession that is already losing talented people to higher paid positions in the private sector.