There are 2 rules involved, which I think can quite often be mixed up.
The first involves leaving space for a car if they have got sufficiently alongside (I think it's FW in front of rear tyres).
The second involves the making of one move to defend your line and then having to leave a car's width, whereas previously the defending driver would just sweep back across to the racing line.
So in the case of Lewis v Alonso in Canada clearly the first rule is irrelevant as Lewis was always behind.
With respect to the second rule, is Alonso, having covered the inside, entitled to move back across the full width of the track? Is it because Lewis was still behind he was entitled to do this? Or is part of the point of the rule that, if denied the inside, the attacking driver should have the room to brake later on the racing line without having to stop earlier to avoid hitting the back of the car in front (or in this case still hit the car in front)? In other words should space be left for the attacking driver to occupy by braking later or does he already need to be alongside?
Or have I cocked it all up and there is in fact one rule?!
