Dear Rich: Simple question: Can my ex-employer stop me from using the customer list I developed when I worked for him? Sorry, but it's not that simple. You should check out this article to determine whether your customer list qualifies as a trade secret. If it doesn't, it's unlikely that it can be protected by state trade secret law or an NDA you may have signed. On the other hand, state laws vary and most states honor noncompete agreements (not California) which may affect your ability to compete against your ex-employer by soliciting his clients. So, if you signed paperwork with your ex-boss, now's the time time to review it (or have an attorney review it).