Headlights must be used from

 Headlights must be used from sunset to sunrise,

Explanation:

due to it getting dark and being dark you need it on from sunset inorder to see the road and prevent  running over animals seeing people cars not hitting others till sun rise untill you can see the roads with out head lights

i think it can have both positive and negative effects on businesses.

for example:

lets say you own a small business and taxes go up 4% that means it is going to cost your business more money to buy product to sell. but at the same time you make more money from the tax rise.

that is my theory.

answer:

conformity to the law or to rules.

explanation: