The lawmaking function of Congress is central to democracy because. it is the means by which the public will becomes public policy. The regular period of time during which Congress conducts its business is called a. ... Under the Constitution, Congress has the sole power to.Lawmaking. The primary function of Congress is to pass rules that all Americans must obey, a function called lawmaking. Congress deals in a huge range of matters, from regulating television to passing a federal budget to voting on gun control.