federal law vs. state law

[gillespie200]

why does the federal law supersede state law?

[Buenchico]

First point: Answerbank is a UK-based site. For a better consideration of matters which relate specifically to US laws, try posting on these sites:

http://answers.yahoo.com/

http://www.answerbag.com/

However, I think that your answer can be found somewhere in here:
http://www.usconstitution.net/const.html
(Basically, the US constitution places the legislative powers of the House of Representatives and of the Senate ahead of all other legislative bodies, such as those of individual states. Similarly, it provides that the Federal judiciary has 'ultimate authority' over all other judicial bodies, such as state courts).

Chris