The CPS, in the shape of its head, Director of Public Prosecutions Alison Saunders, has a bit of a problem here.
The DPP has the responsibility to halt any private criminal prosecutions which are malicious or vexatious.
Two things have already been established in this case.
The police officer in charge - also called Mason - was correct in his view it was his decision whether to prosecute or not.
He took the decision not to prosecute, that decision has been reviewed and not altered.
If Ms Saunders allows the case to proceed, she is effectively saying one or both of the above decisions was wrong.
If the decision not to charge - despite being reviewed - is now deemed to be wrong, then Ms Saunders could exercise her power to order the CPS to take over the prosecution and run it.
The defence may well ask what's changed - other than the victim's family having raised enough money to mount their own prosecution.
New evidence may be a way forward - I'm sure the family has mentioned there may be some.
It would be reasonable for the new evidence to be tested in court, so the CPS could take over the prosecution without too much embarrassment over the original decision not to prosecute.
But for that to happen, the family will have to establish the new evidence is relevant to the case and takes it forward - something which the defence team would probably argue strongly against.
I also suspect the new evidence has already been rejected by the CPS, which is another thing the defence could use in their favour.
If all the above is sorted and we do get a trial, another question is what will the jury be told about all the legal machinations in the case?
One could say 'nothing', but the defence might reasonably argue the fact that the police and CPS originally thought the defendant did nothing illegal - and stuck with that decision under pressure - is relevant to defending the allegation she now faces.
They will certainly want to use the original collision investigation report on which the decision not to prosecute was partly based.
So there's still lots of hurdles for the family to get over.
