Islamic law containing important concepts that apply to all contracts and that cannot be contravened. Based on the Muwatta of Ibn Malik they are the following:
Acts concluded under coercion are invalid
An act is judged by its objective (i.e. a briefly married man who disappears after obtaining residency status).
Contracts are construed based on intention, not words and form.
Lawyers cannot argue the meaning of a point of law or religion when a decisive text exists.
The lesser of two evils and the smaller of two harms is chosen.
The repelling of mischief is preferred to acquisition of benefits.
It is forbidden to ask for a forbidden thing (i.e. a husband or wife may not ask to be free to drink liquor or take drugs in their home).
Common use and custom have force of law.
With a change of times, the requirements of the law change.
Once a right is given up it cannot be reclaimed (i.e. assignment to the wife the right of unconditional divorce upon a husband's marriage to a second wife).
A 15 year old is considered capable of making a nafid (legally binding) contract.
A special guardianship is stronger than a general one (i.e. a father has more right than the state to be guardian if he is not proven to be unjust or unfit.
The unconditional runs with unconditional effect unless by law or indication there is proof of unrestricted effect (i.e. a husband has unconditional right to control his wife's whereabouts in current madhahib unless the wife enters a contract stipulation limiting that effect.)
Promises in a conditional form are binding.
Conformity to conditions is necessary.
A person who commits an act, even unintentionally, is responsible (i.e. a husband spending a wife's income by mixing it with his own money without permission.)
One cannot use another's property without permission (i.e., a father or husband cannot use the mahr of a wife without express permission).
The making of `aqd is the connecting, in a legal manner, the offer (`ijab) and acceptance (qabul), the one with the other in a way which provides clear evidence of mutual connection.
A lawful bay' (changing property for property), called bay' sahih, is one which by substance (zatan) and attributes (wasfan) are consistent with shari'ah.
Bay'fasid is one which is sahih in foundation (assl) but is not consistent with shari'ah.
Bay' batil is a bay' not sound in foundation (i.e. concluding a marriage where the wife is always financially responsible for her own upkeep.)