I can't back this up with direct translations, but it seems like a reasonable solution.

The object of the instant Agreement is to collect royalties due to the Debtor, and Royalty’s failure to seek redress for future infringements or to seek collection on existing payment arrangements would defeat the object of the contract, and certainly constitute a material breach which would result in Debtor’s relief from performance under the contract, that is, payment of Royalty’s commission.

http://www.nysb.uscourts.gov/opinions/cgm/126484_56_opinion....

The concept of change of circumstances is different from force majeure as it does not require impossibility of performance for it to apply and a mere threat of grave loss may suffice. Accordingly, a lower burden of proof than that required under typical force majeure clauses will apply to this doctrine. The courts are required to examine each case based on its own merits and circumstances in order to decide whether or not to grant relief from performance.
http://www.worldfinance.com/news/world-market/energyandenvir...

might fit here

...is probably the phrase you're looking for.

"release from the obligation to perform"
http://shortify.com/11344

A defendant may discharge an obligation to
perform community service under this article by paying at any time
the fine and costs assessed.


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Note added at 9 hrs (2010-10-25 21:41:13 GMT)
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discharge one from obligation to perform