The Latin phrase lex loci means “the local law,” or “rules of the place.” It is the basis of a number of important concepts in law, all revolving around the idea that the place where an action occurred plays an important role in what legal recourse people have and which laws apply to the situation. A contract legal in one region might be less so in another, for example, and so establishing the setting of a crime or cause of action is an important part of moving forward with a legal case, whether criminal or civil.
There are a number of forms of lex loci, all referring to specific issues. Lex loci contractus, for example, is the location where people agreed to or executed a contract. The document must be legal in both places for it to be binding, and legal options for parties to the contract can vary, depending on the specific topic of contention and which region has the applicable laws. Likewise, lex loci actus refers to the place where an act in question occurred, like a car accident at the root of a negligence suit.
Laws vary considerably between jurisdictions and conflicts can arise. Some laws may be completely different, while others have small, but important, variations. When a case comes to court, the parties in the case take steps to establish where the activities in question took place so the court can determine if it has jurisdiction, and what kinds of laws apply to the situation. This can become complex when disputes are international in nature and parties are trying to use the court system to their advantage by pursuing the matter in a court favorable to their side.
The lex loci can mean that an activity illegal in one location is legal in another. People used to doing things a certain way may need to check before repeating the behavior in another place to see if it is permitted and to check on any restrictions. In a simple example, a person with a legal prescription for medical marijuana in one jurisdiction cannot carry the drug in regions where it is illegal in all settings; the local law of the land prevails and the patient could get in trouble.
Differences between jurisdictions explain why attorneys need to pass the bar examination again if they want to practice in a different area; it is vital that they understand how the law works in the area where they want to work. For scholars and attorneys working in the field of international law, knowledge about multiple jurisdictions may be necessary to better understand topics like extradition and treaties.