In Jewish religious law (halacha), a shomer (, pl. , shom(e)rim) is a Jewish legal guardian entrusted with the custody and care of another's object.
The laws of shomrim (pl. "keepers"; "watchmen") are derived from the Torah in the Book of Exodus (Shemot 22:6-14). It is also discussed in the Talmud in the Bava Kamma and Bava Metzia tractates, which deal with torts, usury, and property law.
There are four types of shomrim: an unpaid custodian, a paid custodian, a borrower, and a renter (', ', ', and ', respectively). Each shomer has distinct laws in halacha that apply to it. The two major factors that determine a guardian's liability are whether the guardian has the ability to use the item (i.e., a renter or borrower) and whether money is exchanged. In general, having the ability to use the item and being a paid custodian increase the guardian's liability, while paying for the use of something (i.e., being a renter) decreases the guardian's liability.
Types of shomrim
{| class="wikitable" align="right" style="font-size:90%;"
|+Liabilities of Shomrim
|-
! !! Negligence !! Theft !! Loss !! Unavoidable Damage !! Damage from Normal Wear
|-
! Shomer chinnam
| Yes || No || No || No || No
|-
! Shomer Sakhar
| Yes || Yes || Yes || No || Yes
|-
! Sokher
| Yes || Yes || Yes || No || Yes
|-
! Shoel
| Yes || Yes || Yes || Yes || No
|}
Shomer chinam
A shomer shinam (Hebrew: שומר חנם, pl. שומרי חנם, shomrei chinam), or unpaid watchman, is one who watches an item without receiving payment for his watching. Shomrei cḥinnam are liable only for damages that result from their own negligence. They must pay for damages that result from their negligence. discusses the biblical sourcing of each of the categories of shomrim. The gemara concludes that refers to the shomer ḥinnam, 22:9-12 to the shomer sakhar, 22:13-14 to the shoel, and 22:14 to the sokher.
Becoming a shomer
Generally, one must be willing to become a shomer in order to assume liability, and as such cannot be forced to watch an item. In certain circumstances, such as when one encounters a lost item, the Torah dictates that until the item is returned, the person assumes the liability and responsibility of a shomer sakhar.
The Shomrim's Oath
In order for a shomer to verify the circumstances of the entrusted item's loss, shomrim are required to swear a group of oaths in Beit Din. The oaths required of a shomer typically include swearing how the item was lost, swearing that the shomer had not been negligent, and swearing that the shomer had not misappropriated the item.