A phrase indicating that one is given a lot of independence or is not under very strict control by someone else. Her parents giver her quite a long leash, so it doesn't surprise me that she gets up to as much trouble as she does. They may be regretting the long leash they gave their candidate ahead of the campaign.
a long leash
If someone is given a long leash, they are allowed a lot of freedom to do what they want. Note: A `leash' is a long thin piece of leather or chain, which you attach to a dog's collar so that you can keep the dog under control. He thinks it best to let people have a long leash. `If some want to make fools of themselves, I let them do that, too.' Inga knew that she had to give Judd a long leash or he would have left her. Note: You can say that someone is given a longer leash if they are given more freedom. At the beginning of the campaign, the Republican candidate was given a longer leash than ever before.