A more thorough explanation:

Definition: In rem versum is a Latin term used in Roman law to describe a legal action that is used to one's own advantage. It means that someone is using the law to benefit themselves. For example, if someone sues their landlord for not fixing a leaky roof, they are using the law to their advantage to get the landlord to fix the problem. Example: John filed an in rem versum action against his former business partner to recover money that was owed to him. He used the legal system to his advantage to get the money he was owed. Another example: Mary used an in rem versum action to sue her neighbor for cutting down trees on her property. She used the legal system to her advantage to protect her property rights.