What justice is there when a killer gets sentenced to life in prison at his 70th birthday, for a crime he committed when he was 20? What good is it for a man to be acquitted of a crime, when he has already spent 25 years behind bars? What good is it for a family to receive millions in compensation for some wrongdoing, when they've been living in destitute state for more than a decade?

In all those cases, the victims have not received "justice" for a major, defining, part of their life. That's what the catchy slogan tries to capture.

It makes perfect sense and is a well-known legal saying.

Edit: apparently it may be attributable to William Penn, of Pennsylvania fame.

Is that so? – It rings true to me. The longer justice is delayed the less the population cares about it and people get away with whatever injustice they did.

For whatever reason [0] came to my mind thinking about it.

[0]: https://en.wikipedia.org/wiki/Love_Parade_disaster