Pure legal impossibility is when one engages in conduct he thinks to be illegal, but it actually is legal for him to do.

Situations with pure legal impossibility are not a basis for criminal liability.

Hybrid legal impossibility is when the defendant's goal is illegal but impossible due to the legal status of some factor relevant to his conduct.

Most jurisdictions do not allow hybrid legal impossibility as a defense.

Examples:

• Taking stolen property that turns out to not be stolen
• Trying to bribe a juror when the person is not actually a juror
• Trying to solicit an FBI agent posing as an underage girl in a chatroom
• Trying to hire an undercover cop posing as a hitman