A decision on the expansion of Luton, Stansted and Heathrow airports is to be made on Friday at the High Court.
Several protests have taken place over expansion plans
Groups opposing expansion applied for a judicial review in December after the government released its Air Transport White Paper publication.
The protestors challenged the government on the commercial viability of a second runaway at Stansted airport, as well as other issues.
If the government wins, the White Paper and the runaway plans will go ahead.
If it loses, the whole consultation process which lead to the White Paper may have to begin again and any new runway may be delayed.