It violates the conservation of momentum law, among others. Physical laws have a way of enforcing themselves.
Not trying to be s smart Alec here, but hasn’t quantum physics “defied all the rules” of previously known physics?
Physics defying? LoL! Like I tell my son, it’s called a “Law” for a reason!
The EM Drive was first proposed by a British physicist, Robert Shawyer, in 2001, with his device designed to extract force from the quantum vacuum via a dynamic Casimir effect. Notwithstanding the current negative results, other researchers have claimed to detect a small net thrust. The allure of new physics and extraordinary potential of an EM Drive seem likely to assure continued research and experimentation, even if most of it will never be written up in the scientific literature.