Examples embody the President of Germany , the Queen of the United Kingdom , and the President of Austria . The other necessary model is the presidential system, discovered within the United States and in Brazil. In presidential methods, the executive acts as each head of state and head of government, and has energy to nominate an unelected cupboard. Under a presidential system, the executive branch is separate from the legislature to which it is not accountable. Some countries enable their highest judicial authority to overrule legislation they decide to be unconstitutional. Canon law (from Greek kanon, a ‘straight measuring …