'Every law is an evil, for every law is an infraction of liberty'.

The above is:

An argument is a statement or set of statements that you use to try to convince people that your opinion about something is correct.

Explanation is a reason you give for something that has happened or something you have done.

Justification is a reason, fact, circumstance, or explanation that justifies or defends.

A proposition of fact is a statement which focus largely on belief of the listener in its truth or falsehood. Arguments are aimed at getting listener to accept the statement as being true or false.

Based on the above definitions, the given statement -'Every law is an evil, for every law is an infraction of liberty', will not most certainly fall under the category of Explanation and Justification.

As far as ‘A proposition of fact’ is concerned it requires a pre-existing belief of the listener therefore, the given statement will most certainly will be termed as an argument.