Conditions in Law

From West's Encyclopedia of American Law:

A condition may be either express or implied.

• An express condition is clearly stated and embodied in specific, definite terms in a contract, lease, or deed, such as the provision in an installment credit contract that, if the balance is paid before a certain date, the debtor's interest will be reduced.
• An implied condition is presumed by law based upon the nature of a particular transaction and what would be reasonable to do if a particular event occurred. If a woman leases a hall for a wedding on a certain date, her ability to use the hall is based on its implied continued existence. If the hall burns down before that date, use of the hall is impossible due to fire; therefore, the law would imply a condition excusing the lessor from liability. 

In the law of contracts, as well as estates and conveyancing, conditions precedent and subsequent may exist.

• A condition precedent must occur before a right accrues. A woman may convey her house to her son based on the condition that the son marry by the age of twenty-five. If the son fails to marry by that age, he has lost his right to the house. Similarly, in contract law, if an agreement is signed by one party and sent to a second party with the intention that it will not become enforceable until the second party signs it, the second party's signature would be a condition precedent to its effectiveness. 
• A condition subsequent means that a right may be taken away from someone upon the occurrence of a specified event. An owner of property may convey land to a town on the condition that it be used only for church purposes. If the land conveyed is used to build a shopping mall, then ownership would revert to the original owner. A condition subsequent may also affect a transaction involving a gift. In many states, an engagement ring is regarded as an inter vivos gift to which no conditions are attached. In some states, however, its ownership is considered to be conditioned upon the subsequent marriage of the couple involved; therefore, if a woman does not marry the man who gave her the engagement ring, ownership reverts to him and she must return it to him. 
• Concurrent conditions are conditions in the law of contracts that each party to the contract must simultaneously perform.