Why did Gordon Gould have to endure a lengthy legal battle in order to receive a patent for his innovative laser idea concocted in $1957?$

by $1957,$ several other scientists had filed patents ahead of him, but none of their laser inventions worked

he delayed applying to patent his idea, mistakenly believing he needed to have a working laser to apply

by $1957,$ his laser was no longer the inspiration of a single person.

by $1957,$ his laser technology overlapped previous laser patents.