Barber v. Thomas, No. 09-5201, concerned an action by inmates claiming that the Bureau of Prisons' (BOP) good-time credit calculation method was unlawful because 18 U.S.C. section 3624(b)(1) required a calculation based on the length of the term of imprisonment imposed by the sentencing judge, not the length of time the prisoner actually served. The Court affirmed the Ninth Circuit's affirmance of summary judgment for defendants, on the ground that, because the BOP's method for calculating good time credit reflected the most natural reading of the statute, it was lawful.
As the Court wrote: "Federal sentencing law permits federal prison authorities to award prisoners credit against prison time as a reward for good behavior. 18 U. S. C. § 3624(b). Petitioners, two federal prisoners, challenge the method that the Federal Bureau of Prisons uses for calculating this "good time credit." We conclude that the Bureau's method reflects the most natural reading of the statute, and we reject petitioners' legal challenge."