Annulling Marriages Retroactively in the United States

There is one rabbi in the United States, whose name we cannot specify at this point, who annuls marriages as he pleases, even retroactively after the parties are remarried, based on strange and unfounded reasons. It is well known that Harav Yosef Shalom Elyashiv, shlita, has come out very strongly against his disgraceful acts, but this rabbi continues to do as he pleases and is permitting mamzerim (illegitimately born children) into Klal Yisrael.