Officials in Barnsley, northern England, have given police the power to remove under-16s from the town center between 9 p.m. and 6 a.m. unless they are accompanied by an adult.
The trial rules take effect this weekend and operate for six months.
South Yorkshire Police said the measure would be applied with "discretion" and only target youths engaged in misbehavior.
Rights group Liberty criticized the move, saying the use of age as a basis for removal could face a court challenge. Emma Norton, a lawyer for the group, said "police should target offenders of whatever age, not show disrespect and distrust of a whole generation."
Nick Pickles of the group Big Brother Watch called the measure "a waste of time and resources."