Why has John Boehner (R Speaker of the House) not initiated impeachment proceedings against the President?
US Constitution: Article II, Section 3 states "... he [The President] shall take Care that the Laws be faithfully executed."
The US Constitution does not give the executive branch the ability to change the law or to re-interpret the law. The President is instructed to take Care that the Laws are faithfully executed. He does not have the authority to adhere to only part of a certain law; nor does he have the ability to re-write the law.
But, that's exactly what the President did; essentially, the administration is mis-using its executive authority to implement the DREAM Act in that they have instructed law enforcement to stop deporting young undocumented (uhm, ILLEGAL) immigrants who meet certain criteria.
Executive Order or whatever, the President has no authority to change the law; in fact, he swore an oath to uphold the law. When he created the executive order to rewrite the immigration law, he broke his commitment to uphold the laws of the land.