First, the Australian experience tells us that regular judges and government employees will not cooperate with the merely elected government. So the merely elected government has to rely on the military and on “civilian contractors” (mercenaries). The merely elected government has to give the “civilian contractors” sovereign immunity against the courts, which makes them not very civilian at all. Without sovereign immunity, any time a “civilian contractor” forcibly prevents an “asylum seeker” from going wherever he wills, it will be deemed a war crime, like the Israeli wall.

Secondly you have to find the illegals. What countries that actually have control of their borders do is that local forms of ID are only issued to people with a right to reside there indefinitely. Everyone else either cannot get that ID, or gets a special form of that ID that requires a passport or photocopy of the passport to also be presented. And the foreign passport always shows entry permission which expires after a certain time. And you cannot rent a room, or get a regular job, or open a bank account, or drive a vehicle, etc, without ID. If you are a foreigner, need your passport to rent a room, get a most types of job, or drive a vehicle. Further, if you come to the attention of police, some types of rentacop, or the military guard, they can demand your id, as for example, bad driving, reasonable suspicion of an offense, drunk and disorderly, homeless and no visible means of support, or being obnoxious in a shop or a bar. If the rentacop at the mall detects you are illegally resident, and he does not like you much, he puts you in the mall pen, and calls border control to collect you. The control on renting rooms or buying homes catches far more people more effectively than the control on jobs, since the landlord does not particularly want to rent to illegals, while the employer may well want to hire illegals. And your landlord very much wants your ID so that he can go after you if you trash his stuff, while your employer likely has you under supervision, so does not really want your ID except the government tries, usually not very successfully, to make him. And if a landlord does illegally rent to an illegal, that illegal better be on time with the rent.

Will this catch all eleven million?

No, but it will catch a lot of them, and it will catch the most obnoxious ones, the ones that are causing problems.