“It is essential to the idea of a law, that it be attended with a sanction; or, in other words, a penalty or punishment for disobedience.” —Alexander Hamilton (1787)

In the Federalist Papers, No. 15, Publius  aka Alexander Hamilton argued that the federal must have force behind its laws.  The “passions of men will not conform to the dictates of reason and justice without this constraint.”   Where possible, the punishment should fall on an individual or individuals.  It is necessarily so.  As Hamilton rightly asserted, “…the infamy of a bad action is to be divided among a number than when it is to fall singly upon one” if it is to have any successful influence.

http://www.constitution.org/fed/federa15.htm

What was true then under the Articles of Confederation that first governed our young nation remains true today.   If we have federal laws and individual states or polities within the states are allowed to disregard these laws, we undermine the ability of national government to institute polices.  In some instances, this undermining reaches deeper and becomes an issue of if we are a nation under the rule of law or not. Where this is so and unreasonably so, the federal government should seek enforcement of national laws by the individuals and individual polities refusing to enforce well established laws.  An example given might be that of enforcing our nation’s immigration laws in a reasonable and humane manner.