Which principle allows a jurist to issue a legal opinion on reasoning and public welfare?

Islamic jurisprudence employs various principles to derive legal rulings, especially for matters not explicitly covered in primary texts. The principle that allows a jurist to issue a legal opinion based on reasoning and public welfare (maslaha mursalah) is Istislah. Primarily associated with the Maliki school of thought, Istislah permits jurists to formulate rulings that serve the common good and prevent harm, provided they do not contradict established Islamic principles, thereby addressing new societal needs.

• Qiyas is analogical reasoning, deriving a ruling by comparing a new case to an existing one with a known ruling, based on shared effective cause, not solely public welfare.
• Ijtihad is the broader process of independent reasoning by a qualified jurist to derive a ruling, of which Istislah can be a method, but Ijtihad itself is the *act* of striving for a ruling.
• Ijma' (Jima) is the consensus of Muslim scholars on a legal issue, not an individual jurist's reasoning based on public welfare.