Gun Laws Unenforced by Sheriffs in Colorado, Elsewhere

[From article]
Some sheriffs, like Sheriff Cooke, are refusing to enforce the laws, saying that they are too vague and violate Second Amendment rights. Many more say that enforcement will be “a very low priority,” as several sheriffs put it. All but seven of the 62 elected sheriffs in Colorado signed on in May to a federal lawsuit challenging the constitutionality of the statutes.
[. . .]
In New York State, where Gov. Andrew M. Cuomo signed one of the toughest gun law packages in the nation last January, two sheriffs have said publicly they would not enforce the laws — inaction that Mr. Cuomo said would set “a dangerous and frightening precedent.”

If Obama can enforce or not enforce sections of his signature health care law, why is it a problem for Sheriffs to decline to enforce laws they do not like? Law enforcement agencies have legal discretion about what laws to enforce. The president is obligated to enforce the laws by the Constitution. 

http://www.nytimes.com/2013/12/16/us/sheriffs-refuse-to-enforce-laws-on-gun-control.html?_r=0

Sheriffs Refuse to Enforce Laws on Gun Control
By ERICA GOODE
Published: December 15, 2013