It is as absurd to say, that the power of Congress is limited by these general expressions, "to provide for the common safety, and general welfare," as it would be to say, that it would be limited, had the constitution said they should have power to lay taxes, &c. at will and pleasure. Were this authority given, it might be said, that under it the legislature could not do injustice, or pursue any measures, but such as were calculated to promote the public good, and happiness. For every man, rulers as well as others, are bound by the immutable laws of God and reason, always to will what is right. It is certainly right and fit, that the governors of every people should provide for the common defence and general welfare; every government, therefore, in the world, even the greatest despot, is limited in the exercise of his power. But however just this reasoning may be, it would be found, in practice, a most pitiful restriction. The government would always say, their measures were designed and calculated to promote the public good; and there being no judge between them and the people, the rulers themselves must, and would always, judge for themselves.
Anti-Federalist Papers: Brutus #6