A more thorough explanation:

The prosecution-laches doctrine is a legal defense used in patent infringement cases. It is based on the argument that the patent holder intentionally delayed the issuance of the patent by filing multiple continuing applications that added new patent claims to cover products or processes used after the original application was filed.

For example, if a company filed for a patent on a new type of smartphone, but then continued to file additional applications to cover new features added to the phone, a defendant in an infringement case could argue that the patent holder intentionally delayed the issuance of the patent to gain an unfair advantage.

The prosecution-laches doctrine is also sometimes referred to as the continuation-application laches doctrine or the submarine patent.