http://shlomo-aviner.blogspot.com/2005/07/evidence.html
It doesn't seem to spell out clearly what the issue is with this. I'm very ignorant on matters of niddah. I have no clue what the rabbi was asked to rule on or what was done improperly etc. Perhaps you can explain this? What is this bit about blood being sent??
In short, when there is a question about when a woman's first clean day begins or other such questions, like if she is bleeding due to a scratch or wound as opposed to menstruation, the husband brings or leaves a sample in a bag in a box by the rav's house or to him directly. The rav later calls or writes on the bag whether it is tahor or not.
Shlomo Aviner had many incidents of labeling samples of definite menstrual blood as being tahor (ritually pure). This was what concerned many and brought the issue to Rav Mordekhai Eliyahu who appointed a bet din to investigate.
Shlomo Aviner said he'd show up and accepted the authority of Rav Eliyahu upon himself, yet never showed.
The bet din had nochoice to rule that he can not rule on these issues until further notice.
A long list of mamlachti rabbis, including many from the mamlachti pre-IDF mechinah program, did sign a letter of suport, yet never really stated a halachic case for him to blow off a bet din.
He continued anyway, and there was rabbinical silence for a while. Much later, Rav Levanon, Rav Ya'aqov (ben R' Ovadiah) Yosef, and Rav Lior with the later agreement of Rav Dov Levine of the Jerusalem Bet Din wrote a letter to the religious public stating that when one instructs others to transgress prohibitions which are punsihable by Karet, one may not ask him about any issue, nor read his books nor articles.
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