If you're planning a road trip during the summer holidays, it pays to know you could be penalised more harshly for driving offences across the border than in Canberra.
Although states and territories are responsible for road rules in their own jurisdictions, the laws are more or less uniform nationally, thanks to the Australian Road Rules developed in 1999.
But differences remain between the demerit points issued for rule violations, as well as periods of double demerit penalties.
NSW's penalties are generally higher, and overall more diverse than those in the ACT.
Speeding: Both the ACT and NSW issue one demerit point for speeding above the limit at 10km/h or less, but the similarities end there. If you're caught speeding more than 10km/h over, but less than 20km/h in NSW, you'll receive three demerit points, increasing to four demerit points for between 21km/h and 30km/h over, five points for 30km/h to 45km/h and six points for anything above that level. In the ACT, higher demerit points come only after you're speeding at more than 15km/h over the limit; attracting three points for driving up to 29km/h over, four points between 30km/h and 44km/h, then six points beyond that.
Overtaking: Both the ACT and NSW forbid driving in the right lane of a multi-lane road with a speed limit of more than 80km/h, attracting two demerit points in both jurisdictions. But NSW regards increasing your speed while being overtaken as a more serious offence, one for which you'll accrue three points if caught.
Tailgating: This offence carries a more severe penalty in NSW, warranting three demerit points compared with the ACT's one.
Double demerits: Applicable in both NSW and ACT, double-demerit periods during holidays operate differently in some other jurisdictions. Western Australia also has double-demerit points. Queensland does not have double demerits over holiday periods, but instead issues double the penalty if the same offence is committed twice in 12 months. Victoria, Tasmania and South Australia do not have a double demerits system, while the Northern Territory is considering introducing a scheme after a horror road toll in 2015.
L and P plate laws: The greatest differences between NSW and ACT road rules are those governing drivers on learner or provisional licences. While learners and provisional drivers in the ACT can use mobile phones in phone holders or on Bluetooth to make voice calls, all phone use is forbidden for those licence classes over the border.
Correction: This article has been updated to include Western Australia as a jurisdiction that has double demerit point periods.