Frankpledge
Frankpledge was an English institution in which units (often referred to as a tithing) of ten households were bound together and held responsible for one another's conduct. All men over 12 years of age were joined in groups of approximately ten households. This unit, under a leader known as the chief-pledge or tithing-man, was then responsible for producing any man of that tithing suspected of a crime. The system originated in Anglo-Saxon times, but continued into the Norman period.
http://www.1911encyclopedia.org/Frankpledge
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