When is it legal to drive on the left side of a multi-lane highway?

The legality of driving on the left side of a multi-lane highway is primarily governed by specific traffic regulations, which dictate when vehicles may occupy lanes designated for oncoming traffic safely. The correct context for driving on the left side arises when the intention is to pass another vehicle. In this situation, drivers may temporarily change lanes to overtake slower vehicles, provided it is safe to do so and there are no signs indicating otherwise.

Turning left generally occurs at intersections rather than on a multi-lane highway, where a designated left turn lane is usually provided. Additionally, while avoiding an obstruction could be a reason for temporarily moving into another lane, it does not specifically authorize traveling on the left side as a standard practice. Therefore, passing another vehicle is the most appropriate and acceptable reason for being on the left side of the road in a multi-lane highway context, as it aligns with the rules designed to ensure a smooth and safe flow of traffic.