U.S. District Judge James R. Spencer just sentenced Maureen McDonnell to a year and a day in prison — which is actually better news than if she had been sentenced to exactly a year.
In the federal system, inmates with sentences longer than a year can get them reduced 54 days a year for good behavior. If McDonnell had received a sentence of a year or less, she would not have been eligible.One should not jump to the conclusion that Mrs. McDonnell will actually serve 366 days less 54 days (assuming as is usually the case in white collar crime cases, the defendant qualifies for the good time credit). Rather, the actual incarceration reduction in this case is 47 days. Why?
It is all in how the statute is interpreted. The statute is 18 U. S. C. §3624(b)(1), here. The key language is:
a prisoner who is serving a term of imprisonment of more than 1 year  other than a term of imprisonment for the duration of the prisoner’s life, may receive credit toward the service of the prisoner’s sentence, beyond the time served, of up to 54 days at the end of each year of the prisoner’s term of imprisonment, beginning at the end of the first year of the term,[Note the  is a footnote indication that the original has no comma this point but probably should]
In Barber v. Thomas, 560 U.S. 474, 478-479) (2010), here, the Court, in approving the Bureau of Prison's methodology interpreting the credit to permit only 47 days, used this example (involving a longer sentence but the principle is the same):
Thus, at the end of the first year (Year 1) that prisoner would earn the statute's maximum credit of 54 days. The relevant official (whom we shall call the “good time calculator”) would note that fact and, in effect, preliminarily put the 54 days to the side. At the end of Year 2 the prisoner would earn an additional 54 days of good time credit. The good time calculator would add this 54 days to the first 54 days, note the provisional total of 108 days, and again put the 108 days' credit to the side. By the end of Year 8, the prisoner would have earned a total of 432 days of good time credit (8 years times 54 days). At that time, the good time calculator would note that the difference between the time remaining in the sentence (2 years, or 730 days) and the amount of accumulated good time credit (432 days) is less than 1 year (730 minus 432 equals 298 days, which is less than 365). The 432 days of good time credit that the prisoner has earned by the end of Year 8 are sufficient to wipe out all of the last year of the 10-year prison term and to shorten the prisoner's 9th year of imprisonment by 67 days.
Year 9 of the sentence will consequently become the prisoner's last year of imprisonment. Further, because the prisoner has already earned 67 days of credit against that year (432 days already earned minus 365 days applied to Year 10 leaves 67 days to apply to Year 9), the prisoner will have no more than 298 days left to serve in Year 9. Now the good time calculator will have to work out just how much good time the prisoner can earn, and credit against, these remaining 298 days.
As we said, the statute provides that “good time” for this “last year or portion” thereof shall be “prorated.” Thus, the good time calculator must divide the 298 days into two parts: (1) days that the prisoner will have to serve in prison, and (2) credit for good behavior the prisoner will earn during the days served in Year 9. In other words, the number of days to be served in Year 9 plus the number of good time credit days earned will be equal to the number of days left in the sentence, namely, 298. And to keep the award of credit in the last year proportional to awards in other years, the ratio of these two parts of Year 9 (i.e., the number of good time days, divided by the number of days served) must be 54 divided by 365, the same ratio that the BOP applies to full years served. We can use some elementary algebra, described in the Appendix, infra, to work out the rest. The result is that if the prisoner serves 260 days, he can earn an additional 38 days of credit for good behavior. That is to say, of the 298 days remaining in his sentence, the prisoner will have to serve 260 days in confinement, after which point, his sentence will be fully accounted for (given the additional 38 days' credit earned), and he will be released. In sum, a prisoner subject to a 10-year (3,650-day) sentence who earns the maximum number of days the statute permits will serve 3,180 days in confinement and receive 470 days of “good time” credit, about 15% of the prison time actually served.Thus, in order to achieve a full 54 day credit reduction for the first year, Mrs. McDonnell would have to serve 365 days. But, with the good time credit, she will not actually serve 365 days. Hence, her credit will have to be less, prorated based on her time actually served after the credit is considered. That requires some calculation, but the gurus who do this say that the good time credit is 47 days. Hence, she will have to serve 319 days (366 less 47 days).
I have posted before the on federal good time credit. See particularly paragraph 1 in Another UBS Client Bites the Dust - One Year Sentence (Federal Tax Crimes Blog 9/17/10), here.