In what situation is it permissible to drive in the left lane on a highway in Indiana?

Driving in the left lane on a highway in Indiana is permissible primarily when passing another vehicle. This aligns with traffic laws that encourage the use of the left lane for overtaking slower traffic in the right lane. The rules governing highway driving are designed to facilitate smooth traffic flow and keep the left lane primarily for faster-moving vehicles.

When driving on a multi-lane highway, maintaining proper lane discipline is important. The left lane is intended for passing, while the right lane is generally used for slower-moving or regular traffic. Thus, using the left lane solely for passing helps prevent congestion and enhances road safety by ensuring that faster vehicles can maneuver safely around slower ones.

While there may be scenarios where merging into traffic or the absence of cars in the right lane could tempt a driver to use the left lane, these situations do not justify using the left lane outside of its primary purpose, which is to facilitate safe and efficient passing. Therefore, the only situation that firmly adheres to Indiana's traffic laws regarding left lane usage is when a driver is in the act of passing another vehicle.