Road rules are set by each of the eight state and territories in Australia. Historically, there were many differences between the eight different sets of traffic laws in force in Australia. Since 1948, attempts have been made to develop a single set of rules to cover the whole nation. In the 1990s, the State Governments and the National Road Transport Commission (now the National Transport Commission) started working together to produce the unified rules. The rules adopted reflect the best practises (on safety and economic grounds) and attempted to minimise the potential confusion caused when traveling across borders. The first edition was published on October 19, 1999, and the Australian Transport Council (made of Australia's transport and road ministers) introduced them from December 1999.
When the model rules are changed, it is up to each state and territory to then modify their own legislation. Not all rule changes have been adopted by all states and territories, and sometimes a state or territory has retained an earlier rule. For instance, the change to the urban speed limit from 60 km/h to 50 km/h was not adopted immediately in all states, and has not been adopted at all in the Northern Territory. Similarly, although the Australian Road Rules forbid u-turns at signalised intersections except where explicitly permitted, Victoria retains the state's earlier rule of permitting u-turns except where explicitly forbidden. Since their introduction, there have been amendments in 2003 (twice), and again in 2005.