A more thorough explanation:

A contractual lien is a type of lien that comes from a contract and doesn't depend on common law or statutes. It's like a contract that gives someone a security interest in property. For example, a mortgage is a type of contractual lien.

Some people say that a "contractual lien" shouldn't be called a lien because a "true" lien happens without the property owner's agreement. But others think that the idea of contractual liens is important to talk about in the law.

For instance, if you take out a mortgage to buy a house, the bank has a contractual lien on the property. This means that if you don't pay back the loan, the bank can take possession of the house and sell it to get their money back.