The general rule of the common law forbids creating unreasonable risks of harm to others, which is Oregon’s formulation of negligence law. In most automobile collision cases, the specifications of negligence include lookout, speed, and control. The duty of lookout requires Oregon drivers to keep a reasonable lookout for other drivers, motorcyclists, bicyclists, pedestrians, and people in wheelchairs. If a driver looks but fails to see something which is plainly visible, the Oregon rule is that the driver is still liable in negligence.
The duty of speed requires that the driver drive the speed limit or the speed which is reasonable for the conditions, whichever is less. The speed limit is either the posted speed or depends on the classification of the roadway and neighborhood. Whether a speed is reasonable for the conditions depends on a number of listed factors, but can also include others. The duty of control requires a driver to maintain reasonable control over the vehicle.
In a rear-end collision case, the most common failure is lookout–the offending driver was not looking where he or she was going because they were looking away from the road. A bit less common is the stop in traffic, in which case it is a combination of lookout, speed, and control, and may involve the statutory offense of following too closely. In most non-intentional car collision cases, liabiility will boil down to questions of lookout, speed, and control. It is a very rare case which is a true "accident" where none of the drivers is at fault.