Give somebody enough rope
Definition 1 of 1
Pro Tip 1/3Metaphorical Use
Understand it's not about literal rope, but giving freedom to act until a mistake is made. 
Playing coy, she gave him enough rope to see if he'd lie again.
Pro Tip 2/3Expectation of Failure
It implies the belief that the person will fail when left to their own devices. 
We watched, giving the new hire enough rope to hang himself.
Pro Tip 3/3Strategy Implication
It's often used to describe a strategic decision to not intervene. 
The teacher gave the student enough rope to learn from his own mistakes.