Chazal, the Rambam and the Chofetz Chaim all had confidence in the everyday Yid to make these determinations to be mekayim this Mitzvah. None of them limited performance of this Mitzvah only to the rabbinic or gedolic class.
And the Chofetz Chaim is our master on the issue of Loshon Hora. If he told us to do this Mitzvah then he certainly knew we can and should do it. In fact he cited this Mitzvah in his very sefer Shmiras HaLashon at Hilchos Rechilus 9:15.