The Car at the Ditch

Late one night, two sheriff's deputies on rural patrol in Barry County, Michigan, saw a car swerve off the road at high speed and land in a ditch, its rear jutting onto the roadway and the driver's door open. The deputies stopped to investigate; the Defendant met them near the back of the car, seemed to be under the influence of something, and was slow to produce his license, then failed to produce the registration. When he turned back toward the open driver's door, the deputies followed and spotted a large hunting knife on the floorboard. They patted him down for weapons, finding none. A deputy then shined a flashlight into the passenger compartment to check for other weapons, noticed something under the front seat armrest, knelt partway into the car, and lifted the armrest to find an open pouch that appeared to hold marijuana. The Defendant was arrested and the car impounded; deputies opened the unlocked trunk, finding roughly seventy-five pounds of additional marijuana. At issue is how far officers acting only on safety concerns could go in searching the car and its trunk.