Is reversing on a Northern Ireland motorway ever legal?

Reversing on a Northern Ireland motorway is prohibited except in the most exceptional situation under the direction of police or authorised traffic control.

For Northern Ireland motorists, the key is to use the NI rule rather than assuming a Great Britain article says exactly the same thing. The rule applies to the carriageway, hard shoulder and slip roads as part of the motorway system. Missing an exit is never a reason to reverse.

For this exact issue — “Is reversing on a Northern Ireland motorway ever legal?” — the Northern Ireland motorway rule has to be applied with high-speed safety in mind. Check the live signs, lane status and whether you are dealing with normal driving, congestion or a genuine emergency. Hard shoulders, emergency areas and motorway lanes are controlled spaces, so actions that would be ordinary on a local road can be prohibited or extremely dangerous here.

Continue forward to the next junction even if it adds significant distance to the trip. Where the facts of a journey or vehicle differ from the ordinary case, check the exact DfI/DVA or nidirect rule before travelling rather than extrapolating from a similar situation.

Before publishing this answer, the key factual point in “Is reversing on a Northern Ireland motorway ever legal?” was checked against current Northern Ireland official guidance. That matters because road rules, licence entitlements and enforcement details can differ from Great Britain and can change over time; the sources attached below are the ones to re-check if the rule is updated.