Excellent guest viewpoint.  I would add that local law enforcement does not have the resources to take on enforcing federal immigration law in addition to their current law enforcement responsibilities.  They are already hard pressed to carry out the latter.  Also, if local police are seen as enforcers of federal immigration law, they will lose the trust and cooperation of members of the immigrant community.  Fearful of the police, crimes will go unreported by victims and people will be unwilling to come forth as witnesses to crime.   Those committing crimes will escape arrest and the whole city will be less safe than it is now.  The Lane County sheriff and the chief of EPD do not want to get involved with enforcing federal immigration law for these reasons.

It is state law that law enforcement at the state and local levels cannot arrest people whose only offense is being in the U.S. without papers.  However, if they commit a crime they face arrest and being turned over to ICE.