Mujtahid (qualified jurist)
A jurist qualified to perform ijtihad, that is, to derive rulings from the sources by recognised methods.
A mujtahid is a jurist qualified to perform ijtihad, deriving rulings from the sources of Shariah by recognised methods. AAOIFI's standards speak of interpretations made by a person who is qualified to perform ijtihad, and its fatwa standard expects board members to be well versed in jurisprudence and able to use accepted methods of deriving rulings on new issues. For institutions, the practical question is not the title but the competence: governance rules ask boards to show that their members have the knowledge their decisions require.
Sources
This entry explains a term; it is not a Shariah ruling. Approving a product is for each institution's own Shariah board and regulator.