There seem to be two extreme positions on immigration: completely closed borders and totally open borders. The Constitution, common sense, and the philosophy of freedom offer a principled alternative to these two rash options. [...] The first choice—sending twelve to fifteen million illegals home— isn't going to happen and should not happen. Neither the determination or the ability to accomplish it exists. Besides, if each case is looked at separately, we would find ourselves splitting up families and deporting some who have lived here for decades, if not their entire life, and who never lived for any length of time in Mexico. This would hardly be a Good Samaritan approach to the problem. It would be incompatible with human rights. [...] Due to the immensity of this emotionally charged problem, a simple answer under current conditions will not be easily found.
Ron Paul explains numerous factors that have made immigration into such a contentious issue—when it is traditionally a good thing in a healthy economy. Returning the economy to sound money, and removing government's ability to distort markets by printing infinite dollars for "free" welfare (in this case) would be the most significant steps to make immigration beneficial again. He suggests a number of additional points, from respective private property laws ("No Trespassing" if need be), to introducing a more generous visitor work program, suggests removing automatic citizenship for children born of non-citizens, and rejects both a border fence and national ID. Do give this chapter a full read.