Unless Keith is colossally stupid, he didn't just make up a bunch of stuff when his lawyer told him it's time to be quiet. People have been known to be that stupid in that past , so like someone else said it's good we have a court system to deal with the serious allegations being made by each side.
Even in the criminal justice system, the goal of the criminal justice system has never been to find truth, only produce justice or deterrence.
The last part sounds a bit like a tautology, but essentially, most criminal justice systems were created with the knowledge they can't figure out what really happened in most cases (take murder, where at least one person who knows what happened is dead, and another stands accused), so the goal is usually not to find the truth. Justice is easy, truth is hard.
There are also plenty of cases where truth is irrelevant to the aim of deterrence. It doesn't matter if you catch everyone who is speeding, or even that everyone you ticket was speeding, your goal is usually to get a high enough rate of catching actual speeders to deter the conduct.
Edit: I am referring to the canonical definition of justice, not the bureaucratic one.