How Long Can Ex-Employer Chase Ex-Employee?

Dear Rich: I stopped working for a small California tech company in 2008 and now I'm working for a competitor. My ex-employer recently found out about my job and is threatening to sue because he says I still have trade secrets and that I will disclose them at my new job. Can he still bring a lawsuit after all this time. Isn't there a time limit? There is a time limit for bringing trade secret claims in California. It's three years from the date the trade secret theft was discovered (or should have been discovered with reasonable diligence). So, depending on when you began working and other factors, your ex-employer can probably still bring the suit. That time limit also may depend on whether the ex-employer and you had a written agreement (which may establish its own time limits on secrecy).
Time limits may not be the main issue. According to your letter, your ex-employer is concerned about a prospective disclosure of secrets, not an actual disclosure. If that's the case, that's probably not going to fly in a California court. California law doesn't support claims based on "inevitable disclosures" by former employees (although an ex-employer may be able to get an injunction for a "threatened disclosure"). Here's more on California trade secret law.