Question

Many state and local authorities are requiring cars to have their emissions tested each year. Why would lawmakers need to consult with scientists and mechanics before making these laws?

Answer 1

answer is

the EPA's decision takes precedence.

Step-by-step explanation:

The Supremacy Clause (Article VI, Clause II of the Constitution of the United States of America) states:

"This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding."

This means that the federal government and its laws, treaties and rules have precedence over state or local laws.

Answer 2

So that the laws reduce pollution and have a reasonable cost

I think thats the right one