Key Takeaways

  • Existing patents protect inventions for a limited time, granting exclusive rights to the patent owner.
  • Searching for existing patents requires strategy, including keyword selection, classification codes, and multiple databases.
  • International patent searches are crucial to ensure global protection and avoid infringement.
  • Expired patents enter the public domain and can be freely used.
  • Licensing existing patents can generate revenue without relinquishing ownership.

Existing patents are those that are assigned to an individual or individuals to protect others from manufacturing or selling their inventions. To get a patent, the inventor(s) must file paperwork with the United States Patent and Trademark Office (USPTO) and wait for approval. 

Steps for Searching an Existing Patent

  1. If you have an invention or idea and want to get a patent, you must first search the USPTO database to find out if a patent already exists.
  2. Narrow down your search to be as specific as possible based on what the invention is and its capabilities. You will want to search for both U.S. and international patents.
  3. The USPTO manages three types of patents: utility, design, and plant. Identify which category type fits your invention. The most common is the utility patent, which covers items that produce new results or function in a new way. The design patent covers enhancements to an item that do not affect its functionality. The plant patent covers plants grown using methods such as cuttings or grafts. It does not cover plants that are genetically engineered; these would be covered under utility patents.
  4. Narrow the search even further by choosing the type of search that will produce the most comprehensive and relevant results. Filter the search for areas such as generic, novelty, state-of-the-art, infringement, or validity.
  5. You also have the option, in many cities, of doing an in-person search at a Patent and Trademark Resource Center. The advantage is having access to the hard copies of the patent paperwork. Some resource centers are at libraries, but patent records must be viewed on site.  
  6. If you choose to do online searches, the USPTO database offers multiple options for searching and provides images of the files.
  7. Patent searches are time-consuming because of the need for filtered and multiple searches to provide the appropriate search results applicable to what you need. To ensure accurate results, you may choose to use the services of a patent attorney.

Additional Search Strategies for Existing Patents

In addition to the USPTO database, consider using other patent search platforms such as Google Patents, the European Patent Office's Espacenet, and the World Intellectual Property Organization's PATENTSCOPE. These resources can expand your search globally and help uncover patents filed outside the U.S.

When searching, use a combination of keywords, inventor names, and classification codes (like CPC or IPC codes) to refine your results. The USPTO website also offers tutorials on using Boolean operators and advanced search syntax, which can improve accuracy.

For highly technical or niche inventions, working with a patent attorney or professional searcher ensures you don’t miss critical existing patents, especially ones written with specialized terminology.

Understanding Patent Classifications

Every patent is categorized under a classification system. Familiarizing yourself with these systems—particularly the Cooperative Patent Classification (CPC) or International Patent Classification (IPC)—can streamline your search. By locating the classification code relevant to your invention, you can explore all patents filed under that category, increasing the likelihood of discovering related existing patents.

Con

  • Once an existing patent expires, there is no longer any protection against others infringing on an invention. An expired patent moves to the public domain where it can be used by anyone. 

Risks of Overlooking Existing Patents

Failing to identify existing patents before filing can lead to costly legal disputes, rejected applications, or infringement claims. Beyond legal risks, overlooking prior patents may waste valuable resources developing a product that cannot be patented or commercialized due to overlapping protections.

Conducting a thorough patent search helps avoid "reinventing the wheel" and informs strategic decisions about whether to proceed with a patent application, adjust your design, or explore licensing opportunities.

PRO

  • As a patent owner, you have control over how an invention is used as long as the patent is in effect.
  • When you have an existing patent, it cannot be manufactured, sold, used, imported, or distributed by another individual or company unless the patent owner has been contacted and an agreement is in place between both parties. 

Benefits of Owning an Existing Patent Portfolio

Owning multiple existing patents provides not only legal protection but also a competitive edge in your industry. It can deter competitors from entering your market and increase the valuation of your company during investment or acquisition talks.

Additionally, an existing patent portfolio allows flexibility in monetization—such as selling, licensing, or using patents defensively to negotiate cross-licensing deals with other companies.

Deadline

When a patent is approved, the protection is granted by the USPTO for a limited time. The protection period begins from the date the patent application is filed and generally is in effect for 20 years. 

Maintenance Fees and Renewal Deadlines

For a patent to remain in force throughout its term, maintenance fees must be paid at specific intervals (usually at 3.5, 7.5, and 11.5 years for U.S. utility patents). Failure to pay these fees results in the patent expiring before the full 20-year term, moving it into the public domain.

Be aware that maintenance fee structures vary by jurisdiction, so patent owners managing international portfolios must track deadlines across different countries.

Frequently Asked Questions

  1. Can I use an expired existing patent freely?
    Yes, once a patent expires, it enters the public domain and anyone can use the invention without infringement.
  2. What databases are best for international patent searches?
    Use WIPO's PATENTSCOPE, Espacenet, and Google Patents to search for patents filed globally.
  3. How do I know if a patent is still active?
    Check the patent’s legal status on the USPTO database or international equivalents to confirm if maintenance fees were paid and if the patent remains enforceable.
  4. Is it necessary to hire a patent attorney for a search?
    While optional, hiring a professional ensures a more comprehensive search and reduces the risk of missing critical existing patents.
  5. Can I license an existing patent even if I don’t own it?
    Yes, you can negotiate a licensing agreement with the patent owner to legally use, manufacture, or sell the invention.

If you need help with existing patents, 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.