The Spanish Constitution defines the Senate as 'Chamber of territorial representation'. But in the Senate the provinces are represented, not the Autonomous Communities. The Senate is a Chamber of ‘sober second thought’, subordinated to the lower House, whose will prevails in the event of discrepancy. It lacks specific powers with regard to territorial autonomy; in spite of this, there has been an attempt to assign it relevance in this sphere by creating a General Committee on Autonomous Communities. By way of exception the Senate is exclusively responsible for the decision to authorize the Government to apply measures of ’federal coercion'. This constitutional provision was first activated in October 2017, in the context of the secessionist process in Catalonia, as a result of the repeated noncompliance by the authorities of the resolutions of the Constitutional Court (CC), which concluded with the Unilateral Declaration of Independence (UDI) by Parliament at the same time as the adoption of the measures of federal coercion. The Senate demonstrated that even in a case in which it has the reserved competence, as in the authorization of the adoption of measures of federal coercion, it lacks the capacity to be a federal Chamber.