- David Cameron gambled on settling a 40-year feud over EU membership
- Germany has only limited use of referendums
- The US does not hold national issues on ballots -- it only allows them in individual states
London (CNN)Governments often call referendums as a way out of a political dilemma. But as Colombian President Juan Manuel Santos just found out, referendums don't always produce the expected result and the ramifications can be momentous.