What is the difference between ‘illegal’ and ‘unlawful’? Both the prefixes ‘il-‘ and ‘un’- mean ‘not’. ‘Legal’ and ‘lawful’ are synonyms of each other relating to the law, however there is a slight, but important difference in the usage. You will see a sign that says “Littering is illegal according to town ordinance.” You may also see a sign that says “Littering is unlawful, keep the countryside clean”. The difference between the terms lies in the laws of the land.
Legality has to do with the technicality of laws. For something to be considered ‘illegal’, there has to be a specific law passed by a legislative authority, such as a local or national government that expressly makes it illegal. For example: According to the laws of the country, owning a gun is illegal. There is a specific law that states citizens of this particular country may not own a gun, or they will be punished by the law. ‘Illegal’ also has another common, but unique usage in English. It is used when referring to the official rules of a game. For example: He made an illegal pass in the basketball game.
However, something that is ‘unlawful’ is contrary or goes against the established law, without there being a specific law enacted by a legislative authority to condemn it. This is a broad category, because there are countless acts that are unlawful. No one could ever sit down and enact a specific law against every possibility of wrongdoing. Things that are considered unlawful generally relate to being not morally correct or conventional as well. For example: Putting broken glass on a sidewalk in front of your house is unlawful, because it is dangerous. There isn’t a specific law you are breaking, but you will get in trouble because it is a hazard to public safety which there are laws to protect. In a strictly moral sense, unlawful can be used in a context of an accepted conventionality or way of behaving. For example: The married man had an unlawful passionate affair with his young mistress. The man may not be arrested for his behavior according to the laws of his country, but it is considered wrong by the majority of society.
The difference between ‘illegal’ and ‘unlawful’ is not large, and many times they are used interchangeably. It is important to understand when to use the correct term appropriately. Remember, something that is ‘illegal’ is specifically forbidden, whereas something ‘unlawful’ goes against what is allowed. For example: Someone may say that making a turn on a highway is not illegal, because there is no traffic regulation or sign to specifically say it should not be done. However, because you are only allowed to turn in a designated area for reasons of safety, turning in a non-designated area makes it unlawful or against the law of traffic safety. Both an illegal act and an unlawful act can result in punishment, such as a traffic fine. So it is best to avoid both illegal and unlawful behavior.