However, in a failure to yield case, it becomes much more difficult to know which vehicle had the right of way. The facts are much more tenuous, making it harder to recreate what happened, and the testimony of the drivers and eyewitnesses is important.
For example, in cases where one motorist is making a left in front of an oncoming car, the oncoming driver has the right of way. However, if the oncoming driver was speeding, it could be argued the motorist making the left turn would have had enough room to make that turn if the other driver had been following the speed limit.