Heightened scrutiny is a standard of evaluation that US judges must meet in certain kinds of cases when a policy, rule, or law is brought to a court by someone who wishes to challenge it. It is one of three levels of scrutiny and is also known as intermediate scrutiny. The lower level is the rational basis test, while the highest is strict scrutiny. When judges review laws, they must consider whether they serve the interests of the country while also balancing the need to protect civil liberties.
Some legal scholars object to the interchangeable use of intermediate and heightened scrutiny. Judges may interpret it as a way station between intermediate and strict levels, as some legal discussions of the term define it slightly differently. This reflects shifting attitudes in the legal community and may eventually result in a more formalized split, providing four levels of judicial review instead of three.
The concept of subjecting certain kinds of legal challenges to more rigorous review stems from the equal protection clause in the 14th Amendment to the US Constitution. Whenever a law has the potential to infringe on a civil right, the government must be able to justify the law and show how it meets the goal of protecting national interests. If the law is too broad in scope, does not appear to accomplish what the government claims it does, or creates an unreasonable infringement, a judge must strike it down.
When a judge uses heightened scrutiny, she must first determine that the law does indeed further the interests of the United States in some way. Secondly, she must evaluate the law to see if it is actually relevant to the interests it claims to protect. Some people add a third criteria, a requirement that judges decide if the intrusion the law creates is truly necessary.
People can bring lawsuits to challenge laws or rules passed at any level of the government. When a case involves a claim of civil rights infringement, the judge has to decide on the level of scrutiny to apply to the case. Historically, cases involving any kind of racial discrimination automatically became subject to strict scrutiny. Issues like laws involving gender or sexual orientation tend to fall under heightened scrutiny; for example, Don't Ask Don't Tell, a law banning gay and lesbian service members from serving openly, was subject to this level of scrutiny because it involved discrimination on the basis of sexual orientation.