If my understanding is correct Obama did not change any law. He says he is not going to enforce the law. What would happen if the Border Patrol continue to enforce the law because it is still on the books. Could Obama actually punish agents for enforcing the laws on the books?
You don't understand.
Immigration law has not been changed, the law will continue to be enforced.
Indeed, the deferral program doesn't start for at least another six months. Those wishing to participate must first apply to determine eligibility, those who don't apply or are not eligible are still subject to arrest, prosecution, and deportation. And those participating are still subject to prosecution and deportation if conditions warrant.
Border patrol staff will continue to do their jobs, they'll continue to detain those suspected of being in the country without authorization, where the determination of whether an undocumented immigrant is eligible for deferred action doesn't involve border patrol and other front-line staff.