What Is a Utility Patent and How Long Does Protection Last?

When people refer to "a patent" without any qualifier, they're almost always talking about a utility patent. Utility patents are the most common type granted by the USPTO, covering functional inventions across every technology field imaginable.

What utility patents protect

A utility patent protects how something works, what it does, or how it's made. The patented subject matter must fall into one of five categories under US law:

• A process (method of doing something)
• A machine (a device with moving or interacting parts)
• A manufacture (a product made from raw materials)
• A composition of matter (a chemical compound, mixture, or biological material)
• An improvement to any of the above

Abstract ideas, laws of nature and natural phenomena aren't patentable on their own. But a practical application of those principles can be.

The scope of what's actually protected is defined entirely by the patent's claims, not by the title, abstract, or description. Two patents on "wireless communication" might protect completely different things depending on how their claims are written.

Requirements for a utility patent

To receive a utility patent, the invention must be:

Novel: Not already described in any public disclosure, patent, or prior art anywhere in the world before the application's effective filing date.

Non-obvious: The invention must not be obvious to someone with ordinary skill in the relevant field, even if no exact prior art exists. This is the most litigated requirement.

Useful: The invention must have some identifiable, practical utility. This is rarely a significant hurdle for real inventions.

Adequately described: The application must describe the invention clearly enough that someone skilled in the field could practice it without undue experimentation.

How long a utility patent lasts

For applications filed on or after June 8, 1995, the standard term is 20 years from the earliest effective filing date.

Several factors can modify this:

• Patent term adjustment (PTA) can add days if the USPTO caused unreasonable delays during examination
• Patent term extension (PTE) can add up to 5 years for certain pharmaceutical and medical device patents subjected to FDA regulatory review
• Terminal disclaimers can shorten the term if the owner disclaimed patent term to overcome an obviousness rejection
• Maintenance fee nonpayment causes the patent to expire before the end of its full term

For patents filed before June 8, 1995, different rules apply. Pre-1995 utility patents had a 17-year term measured from grant date and the greater of that or the 20-year term from filing applied.

Maintenance fees are required

Unlike design and plant patents, utility patents require ongoing maintenance fee payments to stay in force. Fees are due at 3.5, 7.5 and 11.5 years after grant. Missing a payment and the grace period that follows causes the patent to expire early.

This means checking maintenance fee status is part of any accurate expiration calculation for a utility patent.

What happens after a utility patent expires

Once a utility patent expires, whether by reaching the end of its term, failing to pay maintenance fees, or a terminal disclaimer shortening the term, the invention enters the public domain. Anyone can practice the claimed invention without a license.

The specification of the expired patent remains a permanent part of the public technical record. Competitors can study it, build on it and cite it. The claims can no longer be enforced, but the disclosed knowledge doesn't disappear.

Utility vs. design vs. plant patents

There are three types of US patents:

Utility patents cover functional inventions. They last 20 years from filing (with adjustments) and require maintenance fees.

Design patents cover ornamental appearance. They last 15 years from grant (14 years for those granted before May 2015) with no maintenance fees.

Plant patents cover asexually reproduced distinct plant varieties. They last 20 years from filing with no maintenance fees.

Most of what gets called "a patent" is a utility patent. The specific rules matter when you're calculating expiration.

The Patent Sunset calculator handles utility, design and plant patents, applying the correct term calculation for each type based on the patent's grant date and prosecution history data.