Is it permissible for scholars to exercise ijtihad regarding matters that have not occurred previously, and what is the evidence for this, other than from a verse or hadith?

It is permissible for a scholar who has reached the rank of Ijtihad to exert his independent reasoning in any unprecedented matter, basing his fatwa on the Qur’an, Sunnah, or the general principles derived from them. This is based on the saying of the Prophet, peace and blessings be upon him: "If a judge makes an independent judgment and is correct, he will have two rewards; and if he makes an independent judgment and is mistaken, he will have one reward."