Couldn't understand the phrase "as is the punishment such denial of freedom constitutes"

Question

I am reading the book "Vocabulary for Writing at University" by Jeanne Godfrey and I came across a sentence that I have had a hard time to understand:

This principle of removing people who harm society is a generally agreed function of prisons, as is the punishment such denial of freedom constitutes.

I think this sentence is trying to say "denial of freedom serves as a punishment", but why would the author express it in this way? And why is that the verb "constitutes" goes to the end of the sentence without an object? Is it common to write in this way?

Answer 1

I can see why you have a hard time with this. There are two complexities.

One is the omitted relativiser: as is the punishment that [such denial of freedom constitutes]. It is perfectly normal to omit it, but here it makes it harder to parse.

Secondly as is X means and X is similarly (whatever came before).

So the whole clause means something like

and [the punishment that such denial of freedom constitutes] is similarly [a generally agreed function of prisons].