Tochigi Prefectural Assembly had already decide to demand the research in Ashio copper mine in 1890, however, because Tochigi was not only the damaged area but also the base of the company possessing Ashio copper mine, the issue became complicated in the assembly, and in 1896 they did not decided anything concerning the mining pollution.
一方、栃木県議会は1890年に足尾銅山の調査を求める議決を行っていたが、鉱毒被害地と足尾銅山双方の地元であるという事情から議会が紛糾し、1896年には鉱毒に関する議決は行わなかった。