blue law
blue law. A statute regulating or prohibiting commercial activity on Sundays. • Although blue laws were formerly common, they have declined since the 1980s, when many courts held them invalid because of their origin in religion (i.e., Sunday being the Christian Sabbath). Blue laws usu. pass constitutional challenge if they are enacted to support a nonreligious purpose, such as a day of rest for workers. — Also termed Sunday law; Sunday-closing law; Sabbath law; Lord’s Day Act. [Cases: Sunday 3–30(8). C.J.S. Sunday §§ 8–83.]