Article IV, Section 4. The United States shall guarantee to every state in this union a republican form of government, and shall protect each of them against invasion; and on application of the legislature, or of the executive (when the legislature cannot be convened) against domestic violence.
Luther v. Borden (1849) established that the Guarantee Clause was something that was not to be reviewed; Baker established the test for whether something is justiciable (political):
1). A textually demonstrable constitutional commitment of the issue to the politicial branches (says expressly in constitution);
2). Lack of manageable standards for judicial resolution;
3). A need for finality in the action of the political branches;
4). Difficulty or impossibility of devising effective judicial remedies
i.. examples of controversies that are non-justiciable - cases concerning war or foreign affairs; matters concerning the structure and organization of the political institutions of the States; cases involving Negro disenfranchisement; abstract questions of political power, sovereignty, of government
Let's put the recent 5-4 Supreme Court decision on the manual recount to the test set in Baker to determine if it is justiciable, and therefore a political decision which the Supreme Court has no authority to rule on...
1)Is the issue at hand (of election procedures) an issue to be decided by political branches?
YES, the Constitution grants the State Legislature the authority to establish the rules of elections, and ultimately it is the canvassing boards of those counties which decide whether or not to recount. Neither the State Legislature of Florida nor the Supreme Court of the United States may overrule that right after the fact.
2)Does the issue at hand demonstrate a lack of manageable standards for judicial resolution?
It would seem so. This issue is unique in our history, and because of its unique nature, no standards have yet been devised to resolve the issue.
3)Does the issue at hand require a need for finality in the action of the political branches?
YES, in disputed elections such as this, where the issue is so close, the need for scrutiny (i.e. recounting ballots) becomes paramount as it is a political decision. The Constitution clearly calls for finality of elections in the Electoral College or in the Congress, if it comes to that.
4)Does the issue at hand demonstrate a difficulty or impossibility of devising effective judicial remedies?
YES, certainly. If the Supreme Court orders an injunction against manual recounts (it has), than its options become either to, in effect, nullify votes (disenfranchising thousands) or to restart the hand recount at such a late date that the outcome will be void due to the deadline restraints set before the Electoral College.
By the test set forward above, the issue at hand regarding the Florida recounts as ordered by the canvassing boards of the various counties falls under the definition of a justiciable or political matter, over which the Supreme Court has no authority of review.
Indeed, the only matter it would seem that they do hold the right of judicial review over is the issue of African-American voter disenfranchisement in Florida, an issue that is specifically declared in case law and in the Constitution itself!
Conclusion: the Supreme Court of the United States, in ordering an injunction against the manual recount of votes in certain Florida counties overstepped its Constitutional authority and based its decision on political grounds, interfering in what is in essence a political matter where it has no jurisdiction.