We do draw a line, and that's that. if we didn't, the miscarriage of justice in Sam Hallam's case would never get to court, as there would never be a court in the first place. A court deals out justice, and in Mr Hallam's case, has just done so. the only difference between the sentencing court and appeal court is the date and time.
Sam Hallam was freed because we draw a line. In other words, the order of the court is the legal fact, regardless of any physical fact. This is not perfect, but it served Mr Hallam wrongly and then served him justly a few years later. Regardless, his freedom is an example of drawing a line under it. If a court makes a decision, only a court, (or Royal pardon, but I digress) can alter that.
Until time travel is a realty, I will support the court system, and yes, I do feel I have lost (civil) cases unfairly in the past, including a judicial review appeal of a public bay I headed up, but respect and accept the court's decision.
One miscarriage of justice is not a pretext to going back to ordeal by fire or lynch mobs.