Legally speaking, do we really have so few friends?

Question

Sanhedrin chapter 3 talks about categories of people who are disqualified from being judges or witnesses in a case. They include some people who are never trustworthy, various relatives of the litigants, and friends or enemies. About this last category, the mishna says:

וְאֵלּוּ הֵן הַפְּסוּלִין: ... הָאוֹהֵב וְהַשּׂוֹנֵא. אוֹהֵב, זֶה שׁוּשְׁבִינוֹ.

A friend or an enemy [is disqualified]. “A friend”: this is one’s groomsman. “An enemy”: anyone whom he has not spoken to in three days because of anger. They replied: “Israelites are not suspected of such.” (3:5)

I looked in the g'mara to see exactly what is meant by "one's groomsman", thinking it meant any time after the designation and wedding, but instead found a discussion about whether the person is disqualified for the seven days of sheva b'rachot or just the first day.

That's rather more narrow than I expected!

Legally speaking, do we really have so few friends? In my own life I can think of people who I'm much closer to than my father's sister's husband, yet the relative I might have no contact with is disqualified while a friend I spend lots of time with, or one who is a business partner, is not assumed to be biased in my favor.

Did this category get broadened in later halachic literature? Who, besides one's groomsman in the week of the wedding, is considered too close a friend to be a judge or witness per halacha?

Answer 1

The mishna is indeed speaking of one's best friend since they were the ones to be grooms in the time. R Adin Steinsaltz explains here

The example that Rabbi Yehuda offered for someone who is a very close friend, or, in the language of the Mishna, who loves him, is shushbino – his “best man.” Shushbinin referred to in this case are the closest friend that a man has.

In Talmudic times the custom was that when a man was to get married, his closest friend would accompany him throughout the days of the celebration. He also bought generous gifts for him and arranged a celebratory meal. This relationship obligated the groom – both morally and legally – to return the favor of shushbinut when his friend or his friend’s son invited him to their wedding. In modern Hebrew the word shushbinin still refers to the close friends of the groom who attend his wedding, but the relationship is not the same as what the Talmud is describing.

But since the mishna then rejects Rabbi Yehuda's opinion, the halacha is that friends can testify for each other, see e.g., the Rambam in MT Edut 13:15

For this reason people who love each other or who hate each other are acceptable as witnesses even though they are not acceptable as judges. For the Scriptural decree disqualifies only relatives as witnesses.

see also SA CM 33:1

Answer 2

The reason we prohibit these people as witnesses is the fear they might perjure themselves. For your groomsman-level best friend you might commit perjury but for other friends not.

Though perhaps you will argue that you also wouldn’t commit perjury for your father’s sister’s husband (ie your uncle). First, even exceptionally honest relatives can’t testify together or about each other (“even Moses and Aaron”). Second, perhaps the intervening relatives will pressure you.

It is easier to apply bright line rules to relatives as the relationship can be defined than to friends where the degree of friendship is inherently a continuous spectrum without clear points of delineation.