I have thought about this issue and it is true that Obama has the power to grant pardons and reprieves, but his power is limited to pardoning and granting reprieves for crimes against the United States. He could stop the prosecution of illegal aliens for entering into the United States and even for breaking such laws as working without a green card or even for using false identification.
However, he does not have the power to grant anyone the right to continue to break the law after amnesty is granted, nor does he have the power or authority to change the status of an illegal alien to a legal resident. He can pardon people for breaking the law, but he can’t unilaterally change the law.
In other words, all he can do is stop the criminal proceedings. He can’t stop the civil proceedings such as deportations based on status defined as unlawful under current law.
So if he grants a blanket amnesty, that will really have no effect on the status of illegal aliens other than to prohibit them from being prosecuted for specific criminal violations done before the amnesty.
Those are all good points, but I think there’s a difference between reprieves and pardons. The constitution says he has both powers. The pardon takes away the vulnerability to prosecution by altogether taking away the crime. The reprieve — when reprieve is defined as relief — means that he can grant them relief. What relief can he grant them that would best fit his agenda?
Work status.
And, as you have so carefully pointed out in the past, once status is granted, some court will find it a violation of our laws to have a group that is in some kind of limbo status — allowed to be in our country but now allowed to file citizenship paperwork. Allowed to work, but not to participate. Some court will find that the equivalent of servitude.