Imprisoned at the age of 16 for the killing of a high school classmate, Mr. Deskovic, now 35, filed a habeas corpus petition in 1997 in Federal District Court contesting his conviction. The court denied the request because the paperwork had arrived four days late. Mr. Deskovic and one of his lawyers  who he said had been misinformed about the deadline for filing  appealed the decision to the federal appellate court on which Ms. Sotomayor sat.

Ms. Sotomayor, along with the other judge on the panel, ruled that the lawyer’s mistake did not “rise to the level of an extraordinary circumstance” that would compel them to forgive the delay. There was no need to look at the evidence that Mr. Deskovic insisted would affirm his innocence, they said.

Mr. Deskovic spent six more years behind bars, until DNA found in the victim not only cleared him, but connected another man to the crime.

Habeas corpus petitions are rarely granted, and Mr. Deskovic knew that all along. Federal judges routinely deny them, including for purely procedural reasons. But he listened as President Obama, in seeking a new Supreme Court justice, talked about how he wanted a judge with not only great intellect, but also great empathy, a judge who knew how the real world worked and who could apply some common sense.

And so Mr. Deskovic is angry. All over again.

“When we filed the appeal, I thought for sure that she and the other judge were going to see the facts of the case, that this wasn’t an error of my doing and that upholding a ruling like that would be a miscarriage of justice,” Mr. Deskovic said.