A more thorough explanation:

Definition: Lex regia is a Latin term that means "royal law." In Roman law, it refers to a law that was supposedly enacted by the Roman people, granting extensive legislative and executive powers to the emperor. Later, it was interpreted to mean that the emperor was a source of law, had complete legislative powers, and that his will or pleasure had the full force of law. Leges imperii is another term used to describe laws that conferred lawmaking and other powers on the emperor.

One example of lex regia is the law that was passed in 27 BCE, which granted Augustus the title of "princeps" and gave him supreme power over the Roman state. This law effectively made Augustus the first Roman emperor and gave him the authority to make laws and govern the empire as he saw fit.

Another example is the law that was passed in 212 CE, known as the Constitutio Antoniniana, which granted Roman citizenship to all free inhabitants of the empire. This law was issued by Emperor Caracalla and was seen as a way to increase the number of people who could be taxed and recruited into the Roman army.

These examples illustrate how lex regia gave the emperor extensive powers to make laws and govern the Roman state. The laws were often used to consolidate power and increase the emperor's control over the empire.