When is overtaking and passing to the right not allowed?

Overtaking and passing to the right is not allowed when it involves driving off the paved portion of the highway. This is primarily due to safety concerns; leaving the paved roadway can increase the risk of losing control of the vehicle or encountering hazardous conditions, such as debris or uneven terrain. In such situations, it becomes difficult to ensure the safety of all road users, including pedestrians and cyclists, who might be on the shoulder or in non-paved areas.

In contrast, the other scenarios provided do allow for overtaking and passing to the right under certain conditions. For instance, when another vehicle is turning left, it's permissible to pass on the right as long as there is sufficient space. Overtaking on a one-way street is typically allowed since all vehicles are traveling in the same direction. During rush hour, traffic flow may be congested, but there are no specific laws against passing to the right as long as it's done safely and legally.