Method vs. system claims

Method claims are different from system, device, or apparatus claims. Method claims are easier to get, but system claims are easier to enforce.

You may have spent time reading patent claims and noticing that the claims tend to repeat. You may see one type of claims reading “system” (or device or apparatus) and another type of claims reading “method.” The two types may look redundant since both seem to describe the same invention. Why did the patent attorney do this?

Different tools for different problems

Systems and methods claims are used by various countries worldwide. The reason why there are multiple types of claims is that, legally, they cover different things. Think of every claim type as a specific legal tool designed to handle a particular legal situation. This article will focus on US law and the American Intellectual Property Law Association (AIPLA) Model Patent Jury Instructions. These give a concise thumbnail sketch of how US patent litigation law handles different claims.

Method claims and contributory infringement

Method claims tend to be easier to write. They often cover the various steps required to use or operate the invention. The courts often allow alternate ways of performing a particular method step. Thus method claims don’t always need as much detail (but beware of “lack of enablement” and “abstract” rejections).

Method claims often target the invention’s users under the legal theory of contributory infringement. From an enforcement (litigation) perspective, method claims have the disadvantage that you must prove that the defendant knew or was willfully ignoring your patent (APLIA 3.10). However, these claims have the advantage that, legally, you are not required to mark your method claims. This gives you more litigation timing flexibility.

System claims and direct infringement

System (or device or apparatus) claims are often harder to write. These cover the relationships between the underlying components of the invention. Patent law requires more detail, such as discussing the underlying structure of the various parts.

System claims usually target the invention’s manufacturers (or counterfeiters) under the legal theory of direct infringement. Someone is infringing if they are making or selling something that reads on the system claims. From an enforcement perspective, system claims are more straightforward because the user’s knowledge and intent don’t matter (AIPLA 3.1). However, one drawback is that you have a higher legal obligation to mark your invention correctly.

An excellent way to get broad coverage is to write patents with different types of claims. This way, you can choose the proper “tool” for your situation.