Who can file a protest in a patent application?

The ability to file a protest in a patent application is open to anyone, which includes not only attorneys but also laypersons who may have an interest in the patent application. This broad allowance is designed to ensure that relevant prior art or information that may affect the patentability of an application can be brought to the attention of the U.S. Patent and Trademark Office (USPTO). The protest procedure allows individuals to raise concerns regarding issues such as prior art that may disclose the claimed invention or raise questions about the patent's novelty and non-obviousness. This practice is intended to improve the quality of patents by encouraging public input and scrutiny during the examination process.

In contrast, the other options are limited in scope. Limiting protests to just patent owners, inventors, or registered patent agents would restrict the flow of valuable information that could influence the examination process and ultimately impact patent validity and enforcement. Therefore, the correct answer accurately reflects the inclusive nature of who is permitted to file a protest.