Legal Definitions - alternative expression

An alternative expression is a term used in patents to describe two or more elements or limitations that perform the same function. For example, a patent claim may include the phrase "iron, steel, or other magnetic material" to describe materials that can be used in a particular invention.

Previously, the U.S. Patent and Trademark Office did not allow alternative expressions in patent claims. However, this policy has changed, and alternative expressions are now permitted as long as they do not create any uncertainty or ambiguity about the scope or clarity of the claims.

Here is an example of how alternative expressions can be used in a patent claim:

Claim 1: A device for measuring temperature, comprising a sensor made of iron, steel, or other magnetic material.

In this example, the alternative expression "or other magnetic material" allows for flexibility in the materials that can be used in the sensor, as long as they have magnetic properties.