To Supreme Court Justices

Today the Supreme Court came to a decision on the recent Arizona immigration law. A lot of the law was struck down, but some of the major aspects of the law were not. I found this very frustrating. I can't understand why we, as a nation, feel like we should keep people from neighboring countries out of this one. Then go a step further and find people that are here "illegally" and deport them. Are they really so threatening seeing as their time is spent hiding from the government and paying taxes they will never benefit from? Would it be better if they just came in offering gifts of blankets laced with small pox? Is that the American dream they should aspire to?