Montana and Nevada were the last remaining U.S. states relying exclusively on the basic rule, without a specific, numeric rural speed limit before the National Maximum Speed Law of 1974. After the repeal of federal speed mandates in 1996, Montana was the only state to revert to the basic rule for daylight rural speed regulation. The Montana Supreme Court ruled that the basic rule was too vague to allow citation, prosecution, and conviction of a driver; concluding enforcement was a violation of the due process requirement of the Montana Constitution. In response, Montana's legislature imposed a limit on rural freeways in 1999.