blackmail, n.All

J. Edgar Hoover directed FBI agents to seize all pornographic materials uncovered in their investigations and forward them to him (to use for his own titillation and as blackmail).

The KGB once tried to blackmail Indonesian president, Achmed Soprano, with sex tapes. Rather than acquiescing, he asked for more copies of the video to show back in his country.

Blackmail is finding out in the present something in the past for use in the future.