Why would the term habeas corpus be used to describe imprisonment?

Back in the olden days Latin (dead language) was considered to be classy.
So all the "smart" people had to learn it.
Now it is habitual for snooty people to set themselves apart by continuing to use it. It sounds so elitist to say "habeas corpus" instead of saying bring me the prisoner so we can see if (s)he is still alive, and well.

The answer to that would be prussia which would later be germany