NDA can be useful when the same person or a company that signed the NDA goes ahead with the idea. When you have a patent, however, and someone replicates whatever is covered by your patent, your prior relationship with that company matters very little. When you have a patent, even people who innocently and coincidentally come out with the same product could be held liable for patent infringement.

But NDA is bad when you attempt to use an NDA as your sole protection, especially when disclosing your idea to people you don’t know and trust fully. If patent protection is available, just having filed for a patent prior to disclosing the idea to a company will put you in a much better position. Filing the application will establish your priority and can prevent them from attempting to patent the idea themselves.The question typically is whether what you have is patentable. If what you have is valuable, and losing it would be devastating or even detrimental to you or your company, it’s worth having an evaluation performed to find out if it is patentable.