In a common law system, judges are obliged to make their rulings as consistent as reasonably possible with previous judicial decisions on the same subject. The Constitution accepted most of the English common law as the starting point for American law. Situations still arise that involve rules laid down in cases decided more than 200 years ago. Each case decided by a common law court becomes a precedent, or guideline, for subsequent decisions involving similar disputes. These decisions are not binding on the legislature, which can pass laws to overrule unpopular court decisions. Unless these laws are determined to be unconstitutional by the Supreme Court, they preempt the common law precedent cases. Judges deciding cases are bound by the new law, rather than the precedent cases.