Local law enforcement officers should be involved in enforcing national immigration laws. The national agencies involved with dealing with immigration need all the help they can get. In order for immigration to be taken care of, it will take all of the law enforcement agencies working together as one unit.
Local law enforcement should not be involved in enforcing national immigration laws because immigration enforcement is a huge job and the local force is not equipped to do it. If local police took on that task, local law enforcement would grind to a halt because it would not be possible for the local police to do both jobs at the same time. Additionally, in our country, the accused as some rights. People of foreign origin living in the USA who might be here legally or might be here illegally need to have recourse to local law enforcement. They might not feel as free to interact with the local police if the local police were Immigration.