What Can (and Can't) Be Patented? A Plain-English Guide

Not every clever idea can be patented. The law draws sharp lines, and knowing which side of them you're on can save you years and thousands of dollars.

Let's walk through exactly what U.S. patent law lets you protect, what it shuts the door on, and the famous court cases that drew those lines.

The Four Categories: §101

Federal law (35 U.S.C. §101) says a patent is available for anyone who invents or discovers a new and useful invention that falls into one of four buckets:

Category	Plain English	Example
Process	A method or series of steps	A new way to purify water
Machine	A device with moving or working parts	An engine, a 3D printer
Manufacture	A made article that isn't a machine	A ceramic-coated pan, a tool
Composition of matter	A chemical compound or mixture	A new drug, an alloy, a plastic

Improvements count too. You don't have to invent the engine from scratch; a genuinely new improvement to an existing engine can earn its own patent.

The word useful matters. Your invention has to actually do something. This is why a perpetual-motion machine can't be patented; it doesn't work, so it isn't useful. The same goes for a vague "idea" with no concrete way to build it.

The Three Things You Can Never Patent

Even if something technically looks like a process or machine, the courts have carved out three permanent exceptions. You cannot patent:

1. Abstract ideas
2. Laws of nature
3. Natural phenomena

The reasoning is simple: these are the basic tools of science and human thought. Letting one person own them would block everyone else. Three Supreme Court cases define the boundaries.

Alice (2014): you can't patent an abstract idea "on a computer"

In Alice Corp. v. CLS Bank, the patent covered the abstract idea of using a neutral middleman to settle financial transactions, simply carried out on a generic computer. The Court said no. Taking an old, abstract concept and adding the words "do it on a computer" doesn't make it patentable.

This is the single most important case for software and business methods today. The question is whether your invention adds a real technical improvement, or just automates a familiar idea.

Mayo (2012): you can't patent a law of nature

Mayo v. Prometheus involved a diagnostic test that linked the level of a drug in a patient's blood to whether the dose should be adjusted. That correlation is a law of nature, a fact about how the body works. Observing and stating it, even with routine steps bolted on, wasn't enough to earn a patent.

Myriad (2013): you can't patent a gene as nature made it

In Association for Molecular Pathology v. Myriad Genetics, the Court ruled that a naturally occurring, isolated DNA segment is a product of nature, so it can't be patented just because someone found and isolated it. But there was a crucial twist: lab-made synthetic cDNA (which doesn't occur in nature) is patentable. The line is between discovering nature and creating something new.

The Other Hurdles: §102, §103, §112

Clearing §101 is just the entrance exam. To actually get a patent, your invention must also be:

• New (§102): It can't already exist in the prior art. If your "invention" was already described, sold, or publicly used, it isn't new.
• Non-obvious (§103): It can't be an obvious tweak that any skilled person in the field would have come up with. This is where many applications fail.
• Fully described and enabled (§112): Your application has to explain the invention clearly enough that someone skilled in the field could actually build and use it. No hiding the ball.

Think of it as four gates in a row. Subject matter, then novelty, then non-obviousness, then disclosure. Miss any one and you don't get through. (Our what is a patent primer covers how these fit into the full process.)

The Quick Lists

CAN be patented:

• A new machine or device, or a real improvement to one
• A new manufacturing or chemical process
• A novel drug, alloy, or composition of matter
• Software that delivers a concrete technical improvement (faster, more secure, more efficient hardware behavior)
• Lab-created synthetic cDNA and other genuinely man-made biological tools
• A new, useful, non-obvious business method with a real technical innovation behind it

CANNOT be patented:

• An abstract idea, even when run "on a computer" (the Alice trap)
• A law of nature or a natural correlation (the Mayo line)
• A naturally occurring substance, including isolated DNA as nature made it (Myriad)
• A mathematical formula or pure algorithm standing on its own
• A bare idea with no concrete implementation
• Anything already in the prior art
• A perpetual-motion machine or anything that doesn't actually work

The Common Questions, Answered

Can you patent software? Yes, but carefully. Software is patentable when it produces a concrete technical improvement, not when it just runs an old abstract idea on an ordinary computer. We go deep on this in how to patent software in 2026.

Can you patent a mathematical formula? No. A pure formula or algorithm is treated like an abstract idea or a law of nature. But a specific machine or process that applies math to achieve a real-world technical result can be patentable.

Can you patent genes? Not as they exist in your body. Naturally occurring isolated DNA is off-limits after Myriad. Synthetic, lab-engineered genetic material is a different story.

Can you patent a business method? Sometimes. Business methods get the same §101 scrutiny as software after Alice. A method that's just a familiar business practice on a computer fails; one tied to a genuine technical innovation can survive.

The Bottom Line

Patent eligibility isn't absolutist, but it is demanding. Your invention has to fit one of the four §101 categories, dodge the three exceptions, and then prove it's new, non-obvious, useful, and fully described.

The single most common reason applications stumble is abstraction, claiming an idea rather than a concrete, working implementation of it. The closer your invention is to a specific, technical, real-world thing that does something, the stronger your footing.