When one of my clients is embroiled in a contract dispute, a common reason is the failure of the contract to plan for contingencies .  For example, a client contracted to buy a house.  The contract, which of course had not been drafted or reviewed by an attorney, called for the client to get a mortgage for X amount of dollars at X percent interest.  The client found he couldn't get the mortgage he had planned.  The contract didn't provide for what would happen if the mortgage fell through. 

So, the client wanted his earnest money deposit back on the grounds that one of the contingencies to the contract, the mortgage, had made the fulfillment of the contract impossible.  The seller insisted that she could keep the earnest money because my client wasn't going to buy the house.   Of course, there was no provision in the contract as to whether and when the earnest money was refundable. 

Throughout the negotiation and drafting of a contract, the parties and their counsel should always be asking themselves "What can go wrong here?"  The contract should then address what happens if it does go wrong.  What if a hurricane flattens the business we were about to sell?  What if the weather never gets warm enough to paint the house by the deadline? 

This eye toward the contingencies is one of the reasons that you should have important contracts reviewed by your attorney before you sign them -- not after.