expression, godan verb (-su)
exile a criminal; banish a criminal
Fixed expression referring to the historical practice of sending a convicted person to a distant island or remote area as punishment. Not used for modern legal deportation.
江戸時代には、重い罪を犯した者を島に罪人を流すことがあった。
In the Edo period, there were cases where serious criminals were exiled to islands.
Compound of 罪人 (criminal) + を (object marker) + 流す (to send away, to banish). The verb 流す here carries the sense of sending someone away to a distant place, a usage dating back to classical Japanese.