Models Available to Parties to Regulate and Distribute Contractual Risk. Hardship Clauses, in Particular

As a consequence of the binding character of contracts, performance must be rendered, despite the added burden it may impose on the debtor. 

However, in order to guard against the possibility of a change of circumstances causing difficultas praestandi, the parties may stipulate hardship clauses, normally in long-term contracts. In the event of hardship, the disadvantaged party is entitled to seek renegotiation. If no agreement is reached in a reasonable period of time, either party may appeal to the courts. If the court finds that hardship exists, it may terminate the contract or adapt its content, in order to restore its equilibrium. 

If a force majeure event occurs, the parties may also provide for substitute performance or a new contractual agreement.