Blocking is one of the most confusing subjects in amateur racing. It is confusing because it often happens without metal-metal contact. As a result, it isn’t reported or protested, and drivers get very little feedback about it. It is also confusing because it isn’t very clearly defined in the rulebooks:
“The overtaken driver is responsible to be aware that he is being passed and not to impede or block the overtaking car. A driver who does not use his rear view mirror or who appears to be blocking another car attempting to pass may be black flagged and/or penalized, as specified in Section 7.”
“The overtaken driver should be aware that he/she is being passed and must not impede the pass by blocking. A driver who does not watch his/her mirrors or who appears to be blocking another car seeking a pass may be black-flagged and/or penalized.”
“Everyone must leave racing room.”
“Drivers must respect the right of other competitors to racing room. Abrupt changes in direction that impede or affect the path of another car attempting to overtake or pass may be interpreted as an effort to deprive a fellow competitor of the right to racing room. The overtaking driver is responsible for the decision to pass another car and to accomplish it safely. The overtaken driver is responsible to be aware that he is being passed and not to impede or block the overtaking car. A driver who does not use his rear view mirror or who appears to be blocking another car attempting to pass may be black flagged and/or penalized.”
There are many blocking scenarios, and it seems likely that sanctioning body officials decided that they’d write the rules in a way that left interpretation up to them. But this doesn’t do much to help the driver who wants to be clean but avail himself or herself of legal racing techniques.
That said, the rules above aren’t really that complicated. In essence, you can’t move off the racing line to obstruct the path of another driver, whether that forces him/her to change line or it deprives him/her of racing room. Those of you in competitive classes will recognize that by this definition there is a lot of blocking in a typical race. If you add the idea that abrupt moves are more likely to be considered blocking, then the number of blocks per race goes down, but there is still plenty going on. A clearer definition would help. For now, we offer that a block is "an abrupt change of direction off the leading driver’s current line which obstructs the line of the following driver and is executed when the cars are close enough that the following driver has little or no time to respond."
We also note that the FIA attempts to clarify, but still leaves the concept of "defending" undefined.
“More than one change of direction to defend a position is not permitted. Any driver moving back towards the racing line, having earlier defended his position off‐line, should leave at least one car width between his own car and the edge of the track on the approach to the corner. Maneuvers liable to hinder other drivers, such as deliberate crowding of a car beyond the edge of the track or any other abnormal change of direction, are not permitted.”
But generally in the U.S. we aren’t racing under FIA rules. So, get all of that Sunday morning F1 watching out of your head when you go to the stewards to make your protest.
And be prepared to have things judged “a racing incident.” For example, here is one of the more famous F1 blocking questions in recent memory:
This was judged to be a racing incident. But it is hard to see how Rosberg doesn’t “deliberately crowd” Hamilton “beyond the edge of the track”. And yet, the argument was made that Hamilton could have backed out of the throttle (“the overtaking driver is responsible for the decision to pass and to accomplish it safely”). The stewards have a hard time interpreting their own rules.
We conclude that you will rarely be called for blocking if there is no contact (and in F1 even if there is contact). Blocking is vaguely defined and even the tightest definition seems to be meaningless in practice.
But the story doesn’t end there. The main reason not to block is that it is dangerous. And in amateur racing, when there is metal-to-metal contact happens, especially if it results in a crash, then the instigator may be called out and in a blocking scenario (unlike passing) the overtaken car will have the burden of proof.
Take a look at this to see an example:
The camera car is not the subject here, but is initially behind two cars that are the subject. The front-runner abruptly moves left and cuts off the middle car. The result is contact but not a crash. The result is also that the camera car easily gets by both of the antagonists.
Interestingly, we talked to the driver who threw the block shown above. He says that he didn’t move the wheel at all, and it is certainly the case that T4 at Road America has a crown in the road that can affect your line. Nonetheless, in blocking what matters is the result, not whether you moved the wheel or what your intent was (something the stewards can’t possibly judge).
This is dangerous. It happens at high speed in this case, but even at lower speeds there can be barriers and other cars and track workers and spectators to hit. If you doubt that it is dangerous, watch this less dramatic block in about the same place but different results:
We would advocate probation and then penalizing drivers who do this stuff. But that will only, slowly, happen if drivers report blocking. As you make your bed, so you must lie in it.