rule of the road

noun4

1. •
   Any of the requirements for how drivers, bicyclists, etc, behave and operate while using public roadways.

   • To obtain a driving licence, you must pass a test to show that you understand the rules of the road.
   • It is a rule of the road in this country that a motorist must yield to a pedestrian who is in a pedestrian crossing.
2. •
   The regulation requiring all traffic (travelling on a road or otherwise) to keep either to the left or the right.

   • The general rule of the road for steamers is precisely the same as the general rule of the pavement for foot passengers in London […] — 1869
3. •
   (nautical) A regulation concerning safe handling of vessels on roadsteads, seaways, sea lanes, etc.
4. •
   (figurative) A basic (fundamental) and general requirement or principle for how to operate or behave in a certain context or domain (for example, an industry, an occupation, a company, an association).

   • You can't fill in fraudulent information on this form if you want to keep your job at this company. That's not a suggestion, that's just a rule of the road around here.