When can you use "patent pending"
Is it legal to put "patent pending" on a product that is on the market that you have not yet filed a patent for?
2 Answers from Attorneys
No. The term "Patent Pending" can only be lawfully used on a product marketed in the U.S. if a U.S. patent application for it has been filed.
For further info on U.S. patents, see the Patent Office Web Site at http://www.uspto.gov
Do not use "Patent Pending" unless you have applied
YES!! Do not use "Patent Pending" unless you know that you have a patent application on file with the Patent Office. In the United States, this means that you have a "Serial Number" for your application (a serial number is assigned to all patent applications, when they are received and accepted as filed in the Patent Office).
The phrase "Patent Pending" puts other potential competitors on notice that you have applied for a patent, and that you are awaiting a determination by the patent office on your invention's patentability. If you decieve others in commerce, you likely make yourself subject to unfair business practice lawsuits, as well as making yourself subject to violation of the Patent laws. If you have a patentable invention, AND if you get your application submitted within one year of the first date that you sold or told others about your invention, then you could lose the right to ever patent the invention because of your misrepresentation of "Patent Pending".
If you have an invention worth protecting, and you need the chilling effect on your competition that "Patent Pending" gives, then consider a provisional application. You should best work with a patent attorney. If you file the Provisional application improperly, you will be limited or perhaps lose the patent that your invention deserves.
This message is provided to assist you in structuring your thoughts when you speak with an attorney about your situation. I am not your attorney, and you are not my client, so this is not legal advice. Legal advice can only be given after a careful interview of the client by the attorney, and I have not had the opportunity to understand the significant issues that I must understand to render legal advice. You should contact an attorney in your state to discuss your situation. That attorney can give you the advice that your situation deserves, after carefully considering the issues that are legally significant in your situation.