Legal Question in Intellectual Property in California

Re: title to a patent

Without a written contract, unless he was your EMPLOYEE, he, not you owns the patent... but you may have a legitimate argument that you have a non-exclusive license to continue using the invention in your project.

You'll want to consult an attorney with all of the details for a more definitive answer.

Re: title to a patent

If you want a dependable answer based on all of the specific information relating to your scenario, you really must go and meet with an attorney specializing in intellectual property law. I am making certain assumptions in attempting to provide some general information and it does not constitute legal advice because I have such limited information provided in your question. With that caveat in mind, I note the following: You indicate that he was a "private contractor" and you were paying "consulting fees". If he were an employee and/or the product was developed as part of your project and on your time, there may be a potential claim for patent rights. Under this scenario, if he was independent contractor and developed the invention at the same time as your project, you probably do not. You also note that you had no agreement that specifically addressed inventions. You do not mention whether you had any other written agreement(s). I suspect you have no claim to his brainchild; however, the best way to be sure would be to consult an experienced intellectual property attorney for a review of all of the available information.