Also, "illegal alien" is an outdated term because implies an individual's entire existence as "illegal," which is dehumanizing.
The "outdated" critique is Orwellian - an attempt to language police and limit the scope of debate by reframing the words and terms used to discuss a complex issue. Newspeak's purpose is to limit freedom of thought and control the population. The aim is to restrict the range of ideas people can express, thereby limiting the range of ideas they can even consider. When we start policing the term "illegal immigrant," we run the risk of narrowing our debate and discussion surrounding immigration policy.
It's also worth considering the consistency of this argument across different domains. For example, nobody is advocating for softening the term "illegal miner". In these contexts, the term "illegal" serves to accurately describe an action that is against the law. It doesn't mean that the individual’s entire identity is reduced to that action, but it does indicate that the action itself is not in compliance with existing laws.
>control the population
Isn't that what immigration departments do?
The phrase "illegal alien" appears in federal law. <https://www.law.cornell.edu/uscode/text/8/1365>