Judges institute a standard to apply to a case, especially when there is a legal precedent. This standard is objective and clear so as to eliminate any ambiguity in terms of how the case ought to be judged. A bright-line standard is an example of such a standard, and it is established in a legal precedent or in a statutory provision.
For example, an individual accused of statutory rape is guilty based only on the age of the minor and the age of the individual who committed the crime. Objective factors such as the age of the involved parties are considered to be a bright-line rule since the resolution of a situation is dependent only on the aforementioned objective factors.
The bright-line rule is in contrast with the balance test, which involves the consideration of all the factors that may have contributed to the crime or act committed. Thus, a balance test may differ from case to case. The difference between a bright-line rule and a balance test is how the case is treated, either as a black or white matter or a case wherein several factors and circumstances must be accounted for.
A legal statute can create a bright-line rule, such as that which determines the people’s right to suffrage. A statute determines who can vote, where one can vote, and how one can vote. A legal precedent can also institute a bright-line rule wherein a judge can provide an opinion that can be applied to other similar cases.