A more thorough explanation:

Constructive possession is a legal term that means having control over something even if it's not physically in your possession. This term is used in criminal and property law.

In criminal law, constructive possession is used to prosecute possession crimes, such as possession of illegal drugs. To establish constructive possession, the person must have knowledge of the object and the ability to control it. For example, if someone has the keys to a safe deposit box that contains illegal drugs, they can be charged with constructive possession of those drugs.

In property law, constructive possession grants the owner the right to obtain physical control and/or a variety of rights over someone else's physical control of that property. For example, if someone rents a storage unit, they have constructive possession of the items stored inside, even though they are not physically in their possession.

It's important to note that constructive possession cannot be established on the basis of ability to control alone. In the case of U.S. v. Bailey, the mere existence of a firearm in a borrowed car could not uphold constructive possession.

John rents a storage unit to store his furniture. Even though he is not physically in possession of his furniture, he has constructive possession of it because he has the keys to the storage unit and the ability to control it.

Another example is if someone has a key to a safe deposit box, they have constructive possession of the contents of that box, even though they are not physically in their possession.

These examples illustrate how constructive possession works in property law.