frivolous

Silly, especially at an inappropriate time or in an inappropriate manner; lacking a good reason for being, or for doing what one does; due to or moved by a whim or caprice.

Of little weight or importance; not worth notice; slight; trivial.

Having no reasonable prospect of success because its claim is without merit, lacking a supporting legal or factual basis, while the filing party is, or should be, aware of this.

There is no easy definition for the phrase 'frivolous lawsuit,' but I imagine any claim for damages where the injuries are minimal or where the basis for the defendant's liability is hard to believe, might qualify as frivolous.

One of the major cost drivers in the delivery of health care are these junk and frivolous lawsuits.