ITL, chapter 4

If they are contrary to law, public order and morality.

When the other party is nonperforming at all, is performing too late (delay) or is performing in the wrong way. (Defective performance)

If a party does not perform, it can be forced to do so by a court.

Expect : 

A case of objective impossibility

when performance requires specific personal qualities

when performance would cause the debtor unreasonable effort or expense

The normal action is for damages, so-called specific performance being the exception.

To hold the nonperforming party liable simply because it did not perform, the wrong party must compensate its customers.

Allow a claim for damages only if he other party was at fault or can at least be held responsible for the nonperformance. (Excuse of force majeur are accepted)