> the opinion adopted when formulating this index

You raise an excellent point. I did a little bit of Googling and discovered:

    > S&P Shariah indices ... are overseen by an independent Shariah Supervisory Board consisting of a panel of internationally renowned Islamic scholars. This board is facilitated by Ratings Intelligence Partners, a London and Kuwait-based Islamic finance advisory firm.

Ref: https://www.ratingsintelligence.com/