From: Raggytash
Date: 09 Jan 18 - 11:18 AM
Even more potential bother for the UK Government it seems they MAY have broken International Law

From your link:

A UN-backed committee has confirmed it is considering a complaint from Friends of the Earth that the government?s EU withdrawal bill breached the Aarhus convention, which requires public consultation on any new environmental law.

"May have broken" (past tense?)
That law (the Withdrawal Bill) has not yet been passed.

"Broken international law": The Aarhus convention is just that, a convention, not a law. Also it is a European convention. That does not really equate with "international" which would seem to suggest relating to all nations.
Also the convention grants the public a right to review changes, once they have happened. So we need to see whether there is an environmental impact of the Withdrawal Bill before deciding whether there is any recourse under the convention.