Re: Reduction to practice - first to invent

No, except in very rare cases this shouldn't happen. One of the requirments to receive a patent is for the invention to be novel (i.e., never done before) and non-obvious (i.e., even though never done before, not easy to come up with). If someone tries to get a patent on your public product, it has been done before by you and they can't get a patent.

What are the rare cases? First, sometimes someone has already filed for a patent when you go to market, but you don't know about it. In that case, they may have invented it independently and they didn't know about your product because it wasn't out yet. One day, you will be selling your product and they will get their patent and they may come ask you for licensing fees or to stop selling your product. This may be fair, because they really did invent it first, you just didn't know about it. Almost everyone wants license fees these days, so it is pretty rare for a patent owner to try to force you to stop and instead they usually just want a small part of your profits. In addition a case came out last year that makes it harder for them to get you to stop without going through a trial.

Second, sometimes the Patent Office makes a mistake and allows a patent they shouldn't have. In this case, the other person may file for a patent after your product comes to market (maybe knowing about your product and maybe not), the Patent Office may not find your product during their search, and they may grant the patent. In this case, the patent is actually invalid, but the patent owner may send you a letter anyway and you will probably want a lawyer to respond about the patent being invalid. This will cost you a little time and money but won't stop you from selling your product.