You're so right in theory, except that they're almost always split along idealogical lines -- individual justices strongly adhere to a single political ideology

You're so right in theory, except that they're almost always split along idealogical lines -- individual justices strongly adhere to a single political ideology, AND justices with similar ideologies almost always stick together. That implies, sadly, that instead of clear first-principles rulings they're really just interpreting the law to suit their beliefs. The split has been studied endlessly and it's real; they rule politically rather than rationally. Just one example of coverage: http://www.theatlantic.com/politics/archive/2012/06/the-incredible-polarization-and-politicization-of-the-supreme-court/259155/ http://www.theatlantic.com/politics/archive/2012/06/the-incr...