The phrase "hadst the law on" means to have legal grounds against someone or to have taken legal action against them. There are various synonyms for this phrase, including "pursue legal action," "file a lawsuit," "enforce legal rights," "initiate legal proceedings," and "exercise legal authority." These expressions are often used to describe situations where someone has violated a law or committed an offense, and legal action is required to hold them accountable. It is important to have a clear understanding of these terms to effectively communicate legal matters with others and to ensure that justice is served.