There were men who had been made impure by a human corpse and could not make the Pesach offering on that day, so they came before Moshe and before Aharon on that day. Those men said to him, "We are impure through a human corpse; why should we be left out by not offering Hashem's offering in its appointed time among the Children of Israel". Moshe said to them, "Stand and I will hear what Hashem will command you".
The Passuk says that the men 'came before Moshe and before Aharon'. Rashi is bothered as to why those men would approach Aharon after approaching Moshe, and says as follows.
לפני משה ולפני אהרן. כששניהם יושבין בבית המדרש באו ושאלום, ולא יתכן לומר זה אחר זה, שאם משה לא היה יודע, אהרן מנין לו. - Before Moshe and before Aharon. They came and asked them when they were both sitting in the Bais Midrash. And it is not possible to say that they asked Moshe and Aharon one after another, for if Moshe did not know, from where would Aharon know?
We find a similar phrase in Parshas Pinchas (כז א-ד) where the Passuk relates the following incident.
ותקרבנה בנות צלפחד וכו' ותעמדנה לפני משה ולפני אלעזר הכהן ולפני הנשיאם וכל העדה פתח אהל מועד לאמר: אבינו מת במדבר וכו' ובנים לא היו לו וכו' תנה לנו אחזה בתוך אחי אבינו: - The daughters of Tzelafchad drew near... And they stood before Moshe, and before Elazar the Kohen, and before the leaders and the entire assembly, at the entrance of the Mishkan, saying. "Our father died in the desert... and he had no sons... Give us a possession among our father's brothers".
There too, Rashi is bothered as to why those men would approach Elazar after approaching Moshe. But what's interesting is that in this other incident, Rashi quotes an additional solution to this question.
לפני משה. ואחר כך לפני אלעזר, אפשר אם משה לא ידע אלעזר יודע, אלא סרס המקרא ודרשהו, דברי רבי יאשיה, אבא חנן משום רבי אלעזר אומר, בבית המדרש היו יושבים, ועמדו לפני כולם. - Before Moshe. And after that, before Elazar?! Is it possible that if Moshe did not know, that Elazar did not know?! Rather invert and interpret the Passuk accordingly [i.e. view the Passuk as saying, "They stood before Moshe, after having already stood before Elazar and before the leaders..."]. These are the words of R' Yoshiyah. Abba Chanan says in the name of R' Eliezer: They were all sitting in the Bais Midrash, and the daughters of Tzelafchad stood before all of them at once.
We need to understand why Rashi was unable to answer that we should invert and interpret our Passuk as well; that indeed, the impure men also approached Aharon before approaching Moshe.
The Rambam (פ"ד מהלכות סנהדרין ה"ח) explains the process of appointing Judges to various factions of Jewish Law, and says as follows. The court should appoint judges, whomever they desire, for particular matters, provided that they are fit to adjudicate all matters. For example, a court has the authority to appoint a remarkable judge who is fit to issue rulings with regard to the entire Torah, and to limit his authority to only rule within specific and limited parameters. For example; they may grant him authority to adjudicate in financial matters but not in forbidden and permitted matters, or in forbidden and permitted matters but not in financial matters. Or they may give him authority to adjudicate in forbidden, permitted and financial matters but not in laws involving financial penalties.
When Yisro advised Moshe (שמות פרק י"ח) to ease from upon himself the burden of judging the multitude of Jews who come to him for judgement, by appointing other Judges who shall judge the minor matters, he told him, והזהרת אתהם את החוקים ואת התורות - And you shall caution them regarding the decrees and the teachings. The Midrash (מכילתא יתרו ב כ) explains this to be referring to the forbidden and permitted matters, with which Yisro was implying that in these matters, it was Moshe alone who was to judge.
Accordingly, when Tzelafchad's daughters were searching for a ruling regarding their father's inheritance, because theirs was a financial inquiry, they were indeed able to approach Elazar and the other leaders before approaching Moshe. Thus, when the Passuk stated that 'the daughters of Tzelafchad drew near and they stood before Moshe, and before Elazar the Kohen, and before the leaders', Rashi was able to explain that we are meant to invert the Passuk and to interpret it as if to say that they stood before Moshe, after having already stood before Elazar and before the leaders.
But when the Passuk says that the impure people 'came before Moshe and before Aharon' for a ruling regarding their impurity, because their inquiry was regarding a forbidden and permitted matter, Rashi was unable to explain that they approached Aharon only before approaching Moshe, for regarding forbidden and permitted matters, only Moshe was able to adjudicate.
(זרע שמשון פרשתנו אות ב)
