I'll Tell You Who Should Apologize for Lynching

The Senate passed a resolution last night apologizing for not enacting anti-lynching legislation sooner than 1964. I'm not going to comment on the appropriateness of such an apology itself; I have another axe to grind.
Let's go to the metaphorical videotape. Congress (Republican Congress, by the way) did in fact enact an anti-lynching law in 1871! Known as the Ku Klux Act, President Grant used the law to control race riots in the South.
Now, who do you suppose intervened? Could it be. . . our robed masters? Why, yes, yes it was. In US v. Harris in 1882, the Supremes ruled that the Ku Klux Act violated the 14th amendment. The reason Congress did not enact an anti-lynching law is because the Supreme Court ruled it had no power to do so! It took until 1964 for the Congress to find its way around the Court --by arguing that lynching was covered under Interstate Commerce!
Incidentally, Justice Kennedy cited Harris in his rationale for striking down the Religious Freedom Restoration Act, passed almost unanimously by Congress in 1993. So apparently the Supreme Court is still officially pro-lynching, no matter how hard the Senate apologizes.
I will ask my thought question again, because until Congress and the President can grapple with this problem, we will never again reign in the courts --even if every Bush nominee gets through unanimously. Is it possible for the Supreme Court to pass down an unconstitutional decision? If it is, are Congress & the President bound by an unconstitutional decision?