Article III is very short. I don't see where it directly gives the authority to "interpret and apply the Constitution" to the Courts.
Perhaps you'd be kind enough to point the wording out?
Let's assume you are correct. Do you seriously contend handing over more power to five lifetime tenure guys in black robes is a good idea?
Article III, Section 2:
The judicial Power shall extend to all Cases, in Law and Equity, arising under this Constitution, the Laws of the United States, and Treaties made, or which shall be made, under their Authority; - to all Cases affecting....(snip, a list of different kinds of cases)... In all Cases affecting Ambassadors, other public Ministers and Consuls, and those in which a State shall be Party, the supreme Court shall have original Jurisdiction. In all the other Cases before mentioned, the supreme Court shall have appellate Jurisdiction, both as to Law and Fact, with such Exceptions, and under such Regulations as the Cognress shall make...”
When it talks about “both as to Law and Fact”, “Law” refers to interpretation of the meaning of the Constitution, laws, or treaty, and “Fact” refers to the facts of the case at hand, which is the APPLICATION of the law to the particular case.
So, for instance, the definition of “natural born citizen” would be an interpretation of the Constitution. Looking at the circumstances of McCain’s birth, for instance, and determining whether he specifically is a natural born citizen would be application of the law to the facts of the case.
Without knowing the definition of “natural born citizen”, a state SOS could obey a law requiring McCain to present his BC, but without a definition of “natural born citizen” that SOS wouldn’t know whether McCain was a natural born citizen or not. And the same thing with Obama based on the dual citizenship issue as well as other things that would be readily apparent if his actual documentation was known.
The judiciary has been able to get away with murder because we the people don’t have any way to hold them accountable - partly because they can always deny standing if they don’t want to rule on something. The system is set up to have a check on the judiciary by allowing the people to amend the Constitution. So if SCOTUS, for instance, would rule that gay marriage is a Constitutional right, the way that the people could check the power of the court to legislate from the bench is by amending the Constituiton, for example, to forbid same-gender marriage.
Of course, activist courts have also denied the people the right to amend their own state Constitutions, so the problem you’re talking about is a real one - and I definitely sympathize with your point.
But just because some referees make bad calls doesn’t mean that you play football without any referees. You have to have referees. You just have to do whatever you can to make them less tempted to make bad calls. Part of that is how judges are appointed and/or approved. We should never have elected Congress-critters who would approve a SCOTUS justice who had falsified the AMA statements on partial-birth abortion in order to push through Clinton’s pro-abortion agenda. What she did is contempt of court, and our elected Congress-critters rewarded Kagan with a SCOTUS position after seeing the contempt she has for the rule of law as well as the role of science? If we had elected decent Congress-critters we could have had some influence over SCOTUS.