The practice of alternative dispute resolution as we know it now began in England in 1066.
To settle personal conflicts, English citizens held their own informal court.
These unofficial gatherings were frequently presided over by respected men in the neighbourhood.
Occasionally the king would follow the citizens' judgment rather than hearing the case in his court.
One of the first types of arbitration ever devised is this one.  In the American Colonies, mediation was more popular than traditional lawyers and courts.
After the United States obtained independence, arbitration was mostly used for patent disputes until the 19th century when the Federal Mediation and Conciliation Service (FMCS) was founded.
Eventually, in the 1920s congress established the “Federal Arbitration Act”.
ADR gained popularity in America throughout the course of the 20th century, and it is now a significant component of the country's legal system.