One truism about imprisonment? There are limits. So imprisonment for serious crimes will come with walls and barbed wires, plus the curtailing of many freedoms that law-abiding citizens enjoy.

Just where the boundaries are, however, can be open to interpretation. Last week, a Circuit Court judge ruled that the state Department of Public Safety (DPS) violated federal law when it ignored an inmate’s requests to engage in certain Native Hawaiian religious practices. DPS was given 28 days to launch a review of Halawa inmate Robert Holbron’s requests, and to offer reasonable alternatives if full accommodation is unfeasible.

Among Holbron’s requests: to gather daily outside for half-hour during sunrise with other Hawaiian inmates to chant and pray, and to worship outdoor at a permanent stone altar.

During trial, the state noted — compellingly, we think — that additional guards to accommodate the daily outdoor dawn worship would cost $421,824 yearly; and that a stone altar raises security concerns, since rocks could be used as weapons or to damage prison property. Further, it didn’t seem that Holbron was being denied equal treatment compared with other-religion practitioners.

Gratifyingly, the judge found no “widespread pattern/practice” of DPS violating federal law, so no changes in policies were ordered. The lesson to DPS, then: Don’t ignore; reasonably accommodate. DPS should be talking with Native Hawaiian practitioners or kahu to scope options.

Bottom line, though: This is prison, where doing time for crime imposes necessary limits for an overriding reason — public safety.