It is known as the “nuclear option” of the Spanish constitution, the button Madrid presses to impose direct rule on any of the country’s 17 autonomous regions. Until today, however, it has never been used, and no one is quite sure what happens next. Spain’s 1978 constitution describes article 155 as an “exceptional or extreme” measure for “situations that are equally exceptional or extreme”. The trigger is defined in the constitution as when a region acts in a “manner which gravely attacked the general interest of Spain”. As outlined in the constitution, Madrid must first inform Mr Puigdemont that it is invoking article 155.…

Source: The Times October 19, 2017 11:03 UTC