Hundreds of Orangemen are parading through Portadown, joined by bands and a crowd of supporters who have not been deterred by the weather.
There have been differences of opinion within the DUP over how to deal with the fallout of the Drumcree dispute.
As an officer, the Upper Bann MP belonged to a small, decision-making committee within the Democratic Unionist Party.
The legal challenge was brought by a member of the Portadown Orange lodge.
The case has been brought by a Portadown Orangeman against Sir Chris Bryant and Jon Boutcher.
People Before Profit’s Gerry Carroll was among several politicians asked to attend interviews over their involvement in the demonstrations on Garvaghy Road.
The attempt to oust them failed as it required cross-community support from a majority of both unionists and nationalists in the assembly.
It follows a decision on Friday by the Secretary of State, Sir Chris Bryant, to ban the march, after receiving police advice.
Judges said their decision was confined to the lawfulness of the decision, not in deciding whether or not the march should occur.
