In which case is it allowed to overtake the oncoming lanes on roads with one lane in each direction?

Explanation

Before moving into an opposing lane to pass, the driver must have a clear stretch long enough to complete the pass and return safely, and must also confirm that no other driver has already begun passing them. Clear road ahead is not enough if moving out would cut across another passing vehicle's path. Likewise, being free of a pass from behind does not create the necessary room when the opposing lane is not clear far enough ahead.