I was reminded of this while skimming through the Supreme Court's decision (PDF) on the Affordable Care Act:
Here, Chief Justice Roberts (the author of the majority opinion) notes a long precedence for the Court to employ a legal principle of charity in assessing the constitutionality of a law. Essentially he is arguing that if there is an interpretation of a law that is constitutional, the court must assume that interpretation.The text of a statute can sometimes have more than one possible meaning. To take a familiar example, a law that reads “no vehicles in the park” might, or might not, ban bicycles in the park. And it is well established that if a statute has two possible meanings, one of which violates the Constitution, courts should adopt the meaning that does not do so. Justice Story said that 180 years ago: “No court ought, unless the terms of an act rendered it unavoidable, to give a construction to it which should involve a violation, however unintentional, of the constitution.” Parsons v. Bedford, 3 Pet. 433, 448–449 (1830). Justice Holmes made the same point a century later: “[T]he rule is settled that as between two possible interpretations of a statute, by one of which it would be unconstitutional and by the other valid, our plain duty is to adopt that which will save the Act.” Blodgett v. Holden, 275 U. S. 142, 148 (1927) (concurring opinion).
This is more than a mere tangent in that the Court's decision to uphold the constitutionality of the individual mandate turns on this point. The Court actively ignores the text of the law (which specifically describes the consequences for not having insurance as "a penalty, not a tax"), and instead interprets the mandate as a tax on non-compliance rather than as a law requiring certain behavior. According to the Court, the government can't mandate the purchase of a certain product (in this case health insurance), but can tax individuals who don't. And this interpretation is a product of employing the principle of charity in interpreting the Affordable Care Act.