I seem to remember something about "justice delayed".
Sure these things are complicated. But coming to a just conclusion sooner rather than later should also be a goal, not just dotting Is and crossing Ts. Of course for law specialists such as lawyers and judges minutiae seem important. But to me it seems the overall goal of the entire concept has been forgotten. Or maybe is ignored on purpose.
The fastest way is leaving it vague, waiting for some court case to set precedent on what is "too long" and use that as a reference for future court cases. Or in this case, it may in fact go to the supreme court who will be able to determine a more concrete time (or just throw it all away and doom us all).
Better to say "you can't hold it for an unreasonable period, and 14 months was unreasonable"
It will have to be resolved at the Supreme Court level anyway, given the US Court of Appeals split.
We're stuck with the courts because congress doesn't do their job, but leaving this to the courts to decide on a case by case basis could mean that only people who can afford to pay the lawyers and court fees and take the time off for a lengthy court battle against the police can expect to have their rights respected. Ideally, we'd have claws with specific limits that would then be used to set department policy. That way it'd be clear to everyone what the expectation is and when a violation occurred.