In Maloney v. Cuomo, Sotomayor signed an opinion of the U.S. Court of Appeals for the Second Circuit that said the Second Amendment does not protect individuals from having their right to keep and bear arms restricted by state governments.
The opinion said that the Second Amendment only restricted the federal government from infringing on an individual's right to keep and bear arms. As justification for this position, the opinion cited the 1886 Supreme Court case of Presser v. Illinois.
They reviewed a similar rights question and ruled in the April 2009 case Nordyke v. King that the Second Amendment did, in fact, apply to the states via the Fourteenth Amendment, heavily citing the Supreme Court in Heller.
Whenever you have a conflict like this, you’re likely to have it end up before the Supreme Court so they can decide the issue. One question Sotomayor must be asked in Congressional hearings is whether she would recuse herself from any review of either of the cases involved -- if she was a member of the Supreme Court.