Reasons: the reasons for classifying cases of invalidity can be grouped under three main headings: initial impossibility, illegality and immorality.
A-initial impossibility: when establishing legal action, the subject of legal action is impossible. In this case, the legal action will be invalid. As an example, the fact that a completely burned house is the subject of a trading contract makes this legal action invalid. So a product that doesn’t exist can’t be sold. In order for the initial impossibility to be put forward, the situation must be objective. Or it was out of the question that items used for religious purposes in Rome were the subject of trading. Therefore, the purchase and sale agreement in which religious equipment was the subject was invalid.
B-illegality: if legal actions are illegal, they are invalid. Although legal sources varied according to the political periods of Rome, in particular, the law of the 12 plates, decisions of the people’s Assembly, decisions of the praetor, orders of the emperor, Corpus Iurus Civilis during the reign of Iustinianus constituted legal sources according to the periods. Therefore, when legal action was taken against these legal sources, the legal action was invalid. According to Roman property law, transactions were made according to the distinction of “res mancipi” and “res nec mancipi” goods. For these,” mancipatio “and” in iure cessio ” were subjected to legal ceremonial procedures. These transactions are stipulated by law. Therefore, the transfer of ownership of the goods must be made in accordance with these transactions. If the transfer of ownership of the goods was not made according to these transactions, the legal proceedings would be invalid. Again, in Rome, there is an oral legal process called “stipulatio”, which is often seen in the law of obligations. This is a legal process established by saying certain words mutually. Here, the words that the parties must say mutually are shaped. Therefore, it was considered invalid in legal proceedings that did not comply with stipilatio’s form requirement.
C-immorality: the subject and purpose of legal proceedings in Rome should not be immorality. Therefore, legal actions made in violation of the general code of ethics are invalid. For example, if a company was established for the purpose of doing illegitimate work, the contract of that company would be considered invalid.