Ramsay MacDonald became Prime Minister due to the Fault Principle
When several alternative governments are viable, negotiations are in practice guided by constitutional principles that determine which actors are asked to form the government and in what order. These principles are referred to as recognition rules in the field of comparative politics and they are often central in narrowing a range of potential government formation options decisively.
In the UK, the prime minister designate is appointed by the Sovereign and asked to form a government. The Monarch is expected to discharge this role in government formation without becoming involved in any negotiations. This is not difficult when a single party commands an outright legislative majority so that the prime minister designate is directly identified by the election result. However, in hung parliaments, the task of naming an appropriate government formateur often involves political choices. Moreover, who is selected as the formateur can have important consequences for the nature of the government that forms. In the past, the UK has applied a range of different principles to select formateurs. The problem is that these principles are potentially contradictory. The need to resolve the contradictions is becoming increasingly pressing in the context of long-term changes in electoral behaviour, which make it unlikely that the hung parliament of 2010 will remain an isolated outcome.
