Very many subjects of Islamic jurisprudence, such as loans, transfer of debts and interdiction are derived from this principle, and the latitude and indulgence shown by Islamic jurists in their rulings are all based upon this rule. Latitude should be afforded in the case of difficulty, that is to say, upon the appearance of hardship in any particular matter, latitude and indulgence must be shown. Injury may not be met by injury. Injury is removed. Necessity renders prohibited things permissible 22.
Necessity is estimated by the extent thereof.
A thing which is permissible by reason of the existence of some excuse thereof, ceases to be permissible with the disappearance of that excuse. When a prohibition is removed, the thing to which such prohibition attaches reverts to its former status of legality. An injury cannot be removed by the commission of a similar injury. A private injury is tolerated in order to ward off a public injury. The prohibition from practice of an incompetent physician is derived from this principle.