United States v. Coons, No. 07-2485-cr (2d Cir. March 30, 2009) (found here)
Coons received a 2-6 year indeterminate New York state sentence for reckless endangerment. He was released on parole, and subsequently arrested and placed in state custody for violating the terms of his parole. He thereafter pled guilty in federal court to being a felon in possession. His federal sentencing was not held, however, until after he'd been in state custody for 16 months.
At sentencing, the court determined his advisory range to be 27-33 months, and sentenced him to 27 months. The sentencing court did not credit Coons for the 16 months that he'd already been in custody, as it could have under U.S.S.G. § 5G1.3(b) and (c). The Second Circuit affirmed, basically holding that the sentencing court affirmatively decided not to give him that credit.
So, yes, Coons could have been in state custody for those 16 months solely because of his parole violation. But the description of the case seems to indicate that his detention was based on the federal gun charges. Even under those circumstances, he was not entitled to credit for the 16 months. But was it fair not to credit him?