In theory, requiring intelligence as a prerequisite for participation in society sounds like a great idea. In practice, it would be the most brutal, repressive, nasty, elitist caste system ever devised by man, which is why I could never in good conscience support it.
First law I'd pass would be a genuine, honest-to-gods balanced budget amendment. Simply, the government cannot, even in times of war, run a deficit. Second law I'd pass would summarily impeach any legislator who added pork to a bill in Congress, "pork" being defined as anything designed solely to benefit that legislator's district or state at the expense of the rest of the country.