Law of Bailment

http://en.wikipedia.org/wiki/Bailment

Tiered system

In many jurisdictions the system of strict liability has been replaced by a tiered system of liability that depends on the relationship of the bailee to the bailor. The bailee is generally expected to take reasonable precautions to safeguard the property, although this standard sometimes varies depending upon who benefits from the bailment.

If both bailor and bailee are found to benefit from the relationship, such as sending a package, then the bailee is held to a standard of ordinary, or reasonable, care. (mutual-benefit bailment)

If the bailment is to the primary benefit of the bailor, such as finding a lost wallet, the bailee must be found grossly negligent to be liable for damage done to the bailment.

If the bailee primarily benefits, such as if you borrow your neighbor's rake to clean your lawn, the bailee must exercise highest care, i.e. is liable for any damages arising from slight negligence.