The supremacy clause combined with interstate commerce clause. Because any action might have a ripple-of-butterfly-wings effect on commerce, the federal law can

The supremacy clause combined with interstate commerce clause. Because any action might have a ripple-of-butterfly-wings effect on commerce, the federal law can claim interstate commerce would be affected. So it can supersede many state laws. You'll find various claims of "State's Rights" where politically convenient vs supremacy clause where convenient depending on political scores.