1. Legal Context (Formal Definition)
In legal terms, “in law” refers to something that is recognized, established, or defined by the legal system. For example:
- “A person is considered an adult in law at age 18.”
→ This means the law officially recognizes someone as an adult at that age. - “In law, theft is defined as the unlawful taking of property.”
→ This refers to the legal definition of theft.
In this sense, “in law” is used to explain what is true according to legal rules, not necessarily according to morality, opinion, or custom.
2. Family Relationships (Informal Usage)
“In-law” is also commonly used to describe relationships created through marriage, not by blood. These are called in-laws. For example:
- Mother-in-law – Your spouse’s mother
- Brother-in-law – Your spouse’s brother or your sibling’s husband
- Daughter-in-law – Your son’s wife
Here, “in-law” means “by legal marriage” rather than by birth. It’s a social and legal way of defining extended family connections.
3. Philosophical or Theoretical Use
Sometimes, “in law” is used in contrast to “in fact” (also called de jure vs de facto).
- “In law, all citizens are equal, but in fact, discrimination still exists.”
→ This means that the law says one thing, but reality might be different.
Summary
- “In law” (legal) = something defined or recognized by legal authority.
- “In-law” (family) = a relative by marriage.
- “In law vs. in fact” = the difference between what the law says and what actually happens in practice.