| A metaphor for fighting down to the last bit of strength and ability. Suggestive of a person fighting using theor fingernails and teeth in a last ditch attempt to stop the opponent. Examples: The NRA would fight tooth and nail to keep the public able to own guns.
The ACLU would fight tooth and nail to keep the U.S. Constitution alive.
Dem bones would fight against the destruction of Everything tooth and nail. | 
