Priority to the right
Priority to the right is a right-of-way system in right-hand traffic, in which the driver of a vehicle is required to give way to vehicles approaching from the right at intersections. The system is stipulated in Article 18.4.a of the Vienna Convention on Road Traffic for countries where traffic keeps to the right and applies to all situations where it is not overridden by priority signs, including side roads and roundabouts.
Usage
The system is widely used in countries with right-hand traffic, including most European countries. What varies, however, is the prevalence of uncontrolled intersections. In some countries, the right of way at virtually all but the most minor road junctions is controlled by the display of priority vs. stop / yield signs or by traffic lights, while in others priority-to-the-right is sometimes applied even at intersections with heavy traffic such as the Place de l'Étoile and on the Boulevard Périphérique.Most states in the United States and provinces in Canada enforce priority-to-the-right at uncontrolled four-way intersections, where motorists must yield to the right, but only if they arrive at the same time.
Uncontrolled intersections are less common in North American, and municipalities increasingly have introduced all way stops, traffic signals and other designations such as multiple lane right-of-way or paved vs. unpaved roads as a means of controlling the intersections to decrease the likelihood of a collision and to make it easier to determine liability in the event of an accident.
https://california.public.law/codes/vehicle_code_section_21800
Some countries use the priority-to-the-right rule, despite driving on the left. Australia uses the priority-to-the-right rule at four-way intersections where the roads all have equal priority, but specific rules apply for T-intersections. Singapore and New Zealand also use priority-to-the-right, as well as priority to vehicles going straight and turning vehicles to give way to vehicles going straight.