In what way? Which Article, Section and Clause did it ignore?
SCOTUS should have stayed out of it and made Congress (& the Florida lege) sort it out... if Congress had been forced to do its duty in sorting out the 2000 election, there would have been more political pressure on them to deal with the usurper 2008 election situation back in January.
Article 2 Sect 1 Clause 2 of US constitution says State legislatures determine how delegates are chosen, not the federal government, which includes the SCOTUS.
This is not to say that Gore would have been elected if a recount was in his favor, Gov Bush already certified the electors. But the SCOTUS stopped the recounting to take the heat so democrats could not blame Jeb for deciding in his brothers favor. It was purely political and the decision applies to so other election according to the SCOTUS ruling.