Elvis' contractual obligation to Colonel Tom Parker, who many liken to the selling of his soul.

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Many disclaimers are, in effect, seeking to impose a contractual obligation unilaterally, and thus are probably unenforceable.

ECONOMIST: Legal disclaimers

And these are not unique and they are part of the contractual obligation.

NPR: Marine Recall Prompts Questions over Iraq Stress

There is a contractual obligation that the student, the parent and the high school guidance counselor are bound to.

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There are enough water bottles, outsized to go cups, nachos and bananas to make them look like a contractual obligation.

BBC: A targeted message from Obama 2012

This is clear in Europe, where a directive from the European Commission tells the courts to strike out any unreasonable contractual obligation on a consumer if he has not freely negotiated it.

ECONOMIST: Legal disclaimers

The retirees point to a 2004 opinion written by then-Attorney General Ken Salazar, now secretary of the Interior in the Obama administration, that a retired public-sector worker's pension "becomes a vested contractual obligation of the pension program that is not subject to unilateral change of any type" by the legislature.

WSJ: Pension Cuts Face Test in Colorado, Minnesota