The body that controls the one variable everything else in reentry depends on: when the person will be at the gate, and how much notice anyone has of it.

That matters because the Commonwealth arrangements built for this moment are keyed to a known release date. A pre-release claim can be lodged only where the release date is known and no more than 21 days away, and where a pre-release appointment can be arranged.

Release dates are not always knowable that far out. Parole decisions, appeals, time served on remand and administrative recalculation can all move a date at short notice, and a person released earlier than expected — or released from remand on the day of a court appearance — is outside the window the pre-release system was designed around.

So the process works well for planned releases from sentence and works worst for the people whose exit is unplanned, which is a large share of the population moving through remand. The pattern is now familiar in this database: an opt-in arrangement that requires foresight reaches the people who had it.