You can't have it both ways.
You can't live in a constitutional republic if you allow the government to act like a police state.
You can't claim to value freedom if you allow the government to operate like a dictatorship.
You can't expect to have your rights respected if you allow the government to treat whomever it pleases with disrespect and an utter disregard for the rule of law.
If you're inclined to advance this double standard because you believe you have done nothing wrong and have nothing to hide, beware: there's always a boomerang effect.
Whatever dangerous practices you allow the government to carry out now--whether it's in the name of national security or protecting America's borders or making America great again--rest assured, these same practices can and will be used against you when the government decides to set its sights on you.
Nothing is ever as simple as the government claims it is.
The war on drugs turned out to be a war on the American people, waged with SWAT teams and militarized police.
The war on terror turned out to be a war on the American people, waged with warrantless surveillance and indefinite detention.
The war on immigration will be yet another war on the American people, waged with roving government agents demanding "papers, please."
So you see, when you talk about empowering government agents to demand identification from anyone they suspect might be an illegal immigrant--the current scheme being entertained by the Trump administration to ferret out and cleanse the country of illegal immigrants--what you're really talking about is creating a society in which you are required to identify yourself to any government worker who demands it.
Just recently, in fact, passengers arriving in New York's JFK Airport on a domestic flight from San Francisco were ordered to show their "documents" to border patrol agents in order to get off the plane.
This is how you pave the way for a national identification system.
Americans have always resisted adopting a national ID card for good reason: it gives the government and its agents the ultimate power to target, track and terrorize the populace according to the government's own nefarious purposes.
National ID card systems have been used before by oppressive governments--in Nazi Germany against the Jews, in South Africa against black citizens, in Rwanda against the Tutsis--in the name of national security, invariably with horrifying results.