Definition
Equal protection is the principle, drawn from the Fourteenth Amendment, that no state may deny any person within its jurisdiction the equal protection of the laws. It requires governments to justify treating one group differently from another.
The guarantee does not forbid all distinctions, since laws constantly classify people, but it requires that those classifications rest on legitimate reasons rather than arbitrary or invidious ones.
Why it matters
How it works
Courts evaluate equal-protection claims using tiers of scrutiny. Most laws need only a rational basis. Classifications based on race or national origin trigger strict scrutiny, demanding a compelling justification. Sex-based classifications fall under an intermediate standard.
The clause originally applied to the states, but courts have read an equivalent guarantee into the Fifth Amendment so that it also restrains the federal government. The result is a broadly applicable command of even-handed lawmaking.