UNIDROIT requires that lost profits be established with a reasonable degree of certainty
By contrast, CISG does not expressly mandate that damages be proved with certainty, but CISG does impose a burden on the claimant to provide evidence of damage
Party Autonomy
Contract parties often recognize the need in their contracts to either specify in advance a method of calculating damages or to limit damages in some fashion
If contract avoided
Art 75 makes clear that the aggrieved party can recover its losses from a “cover” transaction (substitute purchase or sale)
If the aggrieved party did not enter into a cover transaction, then under Art 76 it is still entitled to recover the difference between the contract price and the current market price
In each case, if the aggrieved party has suffered additional damages, then those damages remain recoverable as well under Art 74
Art 50 entitles a buyer to a price reduction is the seller delivers non-conforming goods in the proportion that the actual value the actual delivered goods had at delivery bears to the value that the conforming goods would have had at that time.
Puts injured buyer in the same position as if he had purchased the goods that were actually delivered
Mitigation
like other legal systems, the CISG and the UNIDROIT Principles require the non-defaulting party to take reasonable measures in mitigation of the losses
CISG Art 77 party who relies on a breach of contract must take such measures as are reasonable in the circumstances to mitigate the loss, including loss of profit, resulting from the breach. If he fails to take such measures, the party in breach may claim a reduction in the damages in the amount by which the loss should have been mitigated
