With this now being in the rules it is hoped that there will be no more ambiguity over incidents, this rule comes into force immediately (from the Phoenix Spring races) and applies to all series.19 Corner Rights and Overtaking.
Drivers must establish substantial overlap with the car ahead before they reach the corner's turn-in point to have the right to drive up their inside and attempt to overtake, or to expect them to leave inside room for you. Substantial overlap means at least that the front of your car is in front of the rear wheels of the car ahead (in the green area in the image below - this is enough to trigger the spotter).
In the above example the blue car has good enough overlap to expect racing room in the corner, in this scenario any resulting incident will be judged upon who moved most away or towards the white/yellow or racing line, so if the inside (blue) car drifts up the track into the outside car and there was enough room left by the outside (red) car then responsibility for the incident will rest with the inside (blue) car. Similarly if the outside car does not give enough racing room to the inside car, they will shoulder responsibility for the incident.
In this example the pink car does not have enough substantial overlap before the turn in point and will shoulder the responsibility for any incident that occurs. The ahead driver has the right to be fully committed to the racing line of their choice without any interference if there was no substantial overlap before they turn in. The turn in point is at the reviewers discretion however guidance is given that it is taken from the in game racing line turn in point if one exists.
These rules apply regardless of whether the pass is for position or lapping a backmarker, on the straight a driver being overtaken should always leave enough room for the overtaking car to pass, pushing the car behind onto the apron or squeezing them into the wall is considered blocking and may result in a penalty (even if no yellow happens).
The Penalties for blocking have also been clarified and split into two grades of penalties depending upon what results from it.