Sir - If large numbers of employees from my office building were to descend on the street outside and proceed to block the busy Tottenham Court Road/Euston Road intersection here in central London (let alone the orbital M25 or M1), I would expect the police to come and forcibly remove us, arrest and charge us with obstruction.
If large numbers marched or sat without official permission on a busy city thoroughfare (let alone a traffic-filled freeway) in the United States where I used to live, I would expect the police to act without hesitation to clear the street and to arrest and charge offenders. If large numbers of protesters lay down on Dublin's O'Connell Street or the busy orbital M50, I would expect them to be removed, arrested and charged by gardai.
Ditto for similar protests in any town or city in continental Europe, Asia, Australia, central and south America - nay, on the planet.
So, why not in Northern Ireland?
Henry Smith, Milton Avenue, Highgate, London N6.