smoking gun

We can quibble over whether smoking guns tie the president personally to any corrupt act, or whether the Supreme Court was right to immunize presidents from the scrutiny applied to ordinary citizens.

"A clean signal would be a smoking gun, in my opinion," Silk said.

Dark stars have a smoking gun signature, an absorption feature at 1640 Angstrom, due to the large amounts of singly ionized helium in their atmospheres.

That tape became the so-called “smoking gun” evidence of a Watergate cover-up.

“There is no one smoking gun, and I know that’s problematic for people to understand,” Barger said at a news conference Thursday.