As you begin the process of obtaining a patent, one of your first steps is to conduct a preliminary patent search. A preliminary patent search simply means doing research on what patents already exist to make sure there is not already a similar invention to your own.

A preliminary patent search is also often referred to as a “prior art” search, although a patent search specifically is really just a subgroup of prior art. A prior art search will need to be completed and submitted to the U.S. Patent and Trademark Office (“U.S. PTO”) along with your patent application.

It is the responsibility of the applicant to disclose any relevant information. If the U.S. PTO finds out that you had knowledge about a similar invention and failed to disclose this information with your application, your patent could be legally unenforceable and you may be forced to pay any fees associated with an infringement case. This is why conducting a prior art search is so critical. If you submit a prior art search along with your patent application and the U.S. PTO accepts your patent in light of that, it can be presumed that the patent is valid. This makes it significantly more difficult to challenge in court and can help establish a defense against those seeking to challenge the validity of a patent by trying to find prior art that was not submitted in the original application.

In addition, if a patent owner is trying to seek investors, it is highly likely that any potential investor will do his or her due diligence and assess how strong the patent is from challenges. A prior art search can significantly help strengthen that patent. In addition, if it’s done fairly early on in the process, it can save an inventor a lot of time and money down the road if he or she finds a similar invention and needs to scrap or modify their own. Prior art searches can actually help you if you end up needing to modify your invention. You can see what’s already been done and gain some insight into possible improvements for your invention.

It is often advised that you hire an experienced patent agent or patent attorney to conduct a preliminary prior art patent search. The technical experience they have can be invaluable if you are looking to get thorough, comprehensive results. A patent agent or patent attorney is also bound by a strict code of ethics which requires them to keep confidential any information on the invention and prohibits them from using this knowledge to their personal or financial gain.

However, hiring a patent agent or attorney costs money. If you are looking for a cheaper way to conduct a preliminary patent search, it is probably sufficient for you to do it on your own. To do this, the U.S. PTO offers a free search engine where you can conduct a prior art search on your own.

U.S Patent and Trademark Office’s Patent Search Engine

The U.S. PTO has made a free search engine available to anyone wishing to conduct a preliminary patent search. You can access this database by going to their website at

The agency also put together a comprehensive list of seven steps to follow to conduct a successful search. Those seven steps can be found at This guide covers a wide-ranging source of information from how to find issued and published patents to how to search the U.S. Patent Classification System and the Cooperative Patent Classification Class Schemes.

Other Patent Search Databases

Other patent search engines available at no cost to the public include:


• Delphion Research Intellectual Property Network (this was the former IBM patent site), and

• Source Translation and Optimization (STO) Internet Patent Search System.

Google also has a patent search engine, but it is suggested that you try all of the above mentioned engines first, since Google is more limited in its results.

If you need help conducting a preliminary patent search, you can post your legal need on UpCounsel’s marketplace. UpCounsel accepts only the top 5 percent of lawyers to its site. Lawyers on UpCounsel come from law schools such as Harvard Law and Yale Law and average 14 years of legal experience, including work with or on behalf of companies like Google, Menlo Ventures, and Airbnb.