When you’re locked in fed­er­al pris­on, how old do you have to be to count as “aging”?

That’s the ques­tion two fed­er­al agen­cies are grap­pling over, and the an­swer they pick will de­term­ine how the gov­ern­ment spends more than $800 mil­lion in pub­lic fund­ing for pris­ons. And for tens of thou­sands of fed­er­al in­mates, it could mean the dif­fer­ence between be­com­ing eli­gible for a late-life re­lease pro­gram and spend­ing their twi­light years be­hind bars.

The Fed­er­al Bur­eau of Pris­ons is strug­gling to ad­just to an aging pris­on pop­u­la­tion, a product, in part, of crim­in­al-justice re­forms of the late 1980s that dra­mat­ic­ally re­duced fed­er­al pa­role and im­posed man­dat­ory min­im­um sen­tences for some of­fenses. In fisc­al 2013, the Fed­er­al Bur­eau of Pris­ons spent nearly 20 per­cent of its $6.9 bil­lion budget to in­car­cer­ate in­mates aged 50 and older. And without a policy in­ter­ven­tion, those costs are set to rise: In­mates aged 50 and older make up the fast­est-grow­ing seg­ment of the pris­on pop­u­la­tion, ac­cord­ing to Justice De­part­ment In­spect­or Gen­er­al Mi­chael Horow­itz.

To meet those costs, the Bur­eau of Pris­ons is re­quest­ing a 6.1 per­cent in­crease in fund­ing for fisc­al 2016, an in­crease from the bur­eau’s $6.9 bil­lion budget in 2015.

But in a re­port re­leased in May, the Justice De­part­ment Of­fice of the In­spect­or Gen­er­al sug­ges­ted the Bur­eau of Pris­ons con­sider an al­tern­at­ive solu­tion: ex­pand a “com­pas­sion­ate-re­lease” pro­gram that re­duces the term of im­pris­on­ment for eld­erly in­mates.

To be eli­gible for the re­duced sen­ten­cing pro­gram, in­mates must have “chron­ic or ser­i­ous med­ic­al con­di­tions re­lat­ing to the aging pro­cess” that “sub­stan­tially di­min­ish their abil­ity to func­tion in a cor­rec­tion­al fa­cil­ity” for which “con­ven­tion­al treat­ment prom­ises no sub­stan­tial im­prove­ment,” ac­cord­ing to a state­ment from the Bur­eau of Pris­ons. They must also have served more than half of their sen­tence. For in­mates look­ing for early re­lease un­der non­med­ic­al cir­cum­stances, the time-served bar is high­er: “the great­er of 10 years or 75 per­cent of their term.”

“As with all com­pas­sion­ate-re­lease de­term­in­a­tions, the BOP con­siders wheth­er the of­fend­er poses a danger to the safety of an­oth­er per­son or to the com­munity,” the state­ment said.

But for any of the above cri­ter­ia to be con­sidered, the in­mate must be aged 65 or older.

The In­spect­or Gen­er­al re­port did not ex­pli­citly call on the Bur­eau of Pris­ons to lower the lim­it in its May re­port. In­stead, it re­com­men­ded the bur­eau re­con­sider the age bar and noted the po­ten­tial ad­vant­ages of set­ting it at age 50.

The lower threshold would cut in­car­cer­a­tion costs and re­lieve pris­on over­crowding without sig­ni­fic­antly in­creas­ing re­cidiv­ism rates, the re­port said. The re­port notes sev­er­al ways in which pris­on­ers 50 and over dif­fer from the rest of the pris­on pop­u­la­tion. Older in­mates cost an av­er­age of 8 per­cent more to con­fine, but they are also less likely to end up back in pris­on after re­lease. While the re­cidiv­ism rate among all pris­on­ers is 41 per­cent, for those re­leased after age 50, the rate falls to 15 per­cent.

Ac­cord­ing to the In­spect­or Gen­er­al re­port, lower­ing the threshold age from 65 to 50 and in­sti­tut­ing a 5 per­cent re­lease rate for only those in­mates in min­im­um or low-se­cur­ity in­sti­tu­tions or med­ic­al cen­ters could re­duce in­car­cer­a­tion costs by ap­prox­im­ately $28 mil­lion per year.

Fed­er­al pris­ons with the most aging in­mates spent “five times more per in­mate on med­ic­al care” and “14 times more per in­mate on med­ic­a­tion” than in­sti­tu­tions with the few­est aging in­mates, the re­port said.

The 65-or-over bar for the pro­gram is re­l­at­ively new, set in 2013 in an ef­fort to cla­ri­fy the re­lease pro­gram’s eli­gib­il­ity cri­ter­ia fol­low­ing a sep­ar­ate In­spect­or Gen­er­al re­port re­leased earli­er that year.

The two agen­cies split over how ef­fect­ive the pro­gram has been since that time. The In­spect­or Gen­er­al re­port said that between Au­gust 12, 2013, and Septem­ber 12, 2014, only two of the 348 in­mates who were qual­i­fied to make re­quests were let out.

The Bur­eau of Pris­ons said that the In­spect­or Gen­er­al re­port does not present “the full pic­ture.” From Au­gust 2013 to Au­gust 11, 2015, 21 eld­erly in­mates without med­ic­al con­di­tions and sev­en eld­erly in­mates with med­ic­al con­di­tions have been re­leased un­der the pro­gram, the bur­eau state­ment said.

For now, it’s un­clear wheth­er the Bur­eau of Pris­ons will lower the min­im­um age for its com­pas­sion­ate-re­lease pro­gram.

In its re­sponse to the May In­spect­or Gen­er­al re­port, the agency said it would “raise the is­sue with rel­ev­ant stake­hold­ers for fur­ther dis­cus­sion.” It also, however, noted that the In­spect­or Gen­er­al re­port wasn’t ex­pli­citly re­com­mend­ing a lower age, in­stead only re­com­mend­ing that the change be con­sidered.