On the first day of Sonia Sotomayor's hearings, senators on both sides of the aisle have taken the opportunity to revive old battles, including the Democrats' successful filibuster of appellate court nominee Miguel Estrada in 2001.

"If a compelling life story, academic and professional excellence, and a top ABA [American Bar Association] rating make a convincing confirmation case, Miguel Estrada would be a U.S. Court Circuit Judge today," said Sen. Orrin Hatch, R-Utah. "But he was fiercely opposed by groups, and repeatedly filibustered by Democrat senators, the ones who today say these same factors should count in Judge Sotomayor's favor."

Hatch's argument was echoed by Sen. Lindsey Graham, R-S.C., in his opening remarks, and later Judiciary Chairman Patrick Leahy, D-Vt., and ranking member Jeff Sessions, R-Ala., briefly squabbled over what -- if anything -- Republicans could have done to make sure Estrada was confirmed.

Democrats filibustered Estrada, many say, because George W. Bush was likely to pick him for the high court down the road. Graham noted today that Estrada rather than Sotomayor might have been the nation's first Hispanic justice.

ABC News' Jan Crawford Greenburg has an interesting take on the revived battle here.