Agreement procedures are conducted by the judicial system of our country. And if an agreement does not exceed laws and regulations, it is considered an illegal agreement. The following examples clearly show that not all contracts concluded between the parties are valid, some fundamental elements that make the treaty illegal or illegal. So the next question is what makes the treaty illegal. to which it will be answered in this article. A contract is an agreement that specifically defines the rights of the parties, the performance of an act that each party must perform, taking into account the limits defined in its name. It also serves as evidence when a claim needs to be proven in court. What is the difference between “illegal” and “illegal”? Both prefixes mean `il-` and `un`- `not`.