tion instead of a tax. But this act is more. It provides a heavy exaction for a departure from a detailed and specified course of conduct in business. That course of business is that employers shall employ in mines and quarries, children of an age greater than sixteen years; in mills and factories, children of an age greater than fourteen years, and shall prevent children of less than sixteen years in mills and factories from working more than eight hours a day or six days in the week. If an employer departs from this prescribed course of business, he is to pay the Government one-tenth of his entire net income in the business for a full year. The amount is not to be proportioned in any degree to the extent or frequency of the departures, but is to be paid by the employer in full measure whether he employs five hundred children for a year, or employs only one for a day. Moreover, if he does not know the child is within the named age limit, he is not to pay; that is to say, it is only where he knowingly departs from the prescribed course that payment is to be exacted. Scienter is associated with penalties not with taxes. The employer's factory is to be subject to inspection at any time not only by the taxing officers of the Treasury, the Department normally charged with the collection of taxes, but also by the Secretary of Labor and his subordinates whose normal function is the advancement and protection of the welfare of the workers. In the light of these features of the act, a court must be blind not to see that the so-called tax is imposed to stop the employment of children within the age limits prescribed. Its prohibitory and regulatory effect and purpose are palpable. All others can see and understand this. How can we properly shut our minds to it?
It is the high duty and function of this court in cases regularly brought to its bar to decline to recognize or enforce seeming laws of Congress, dealing with subjects not entrusted to Congress but left or committed by the supreme law of the land to the control of the States. We can not avoid the duty even though it require us to refuse to give effect to legislation designed to promote the highest good. The good sought in unconstitutional legislation is an insidious feature because it leads citizens and legislators of good purpose to promote it without thought of the serious breach it will make in the ark of our covenant or the harm which will come from breaking down recognized standards. In the maintenance of local self government, on the one hand, and the national power, on the other, our country has been able to endure and prosper for near a century and a half.
Out of a proper respect for the acts of a coordinate branch of the Government, this court has gone far to sustain taxing acts as such, even though there has been ground for suspecting from the weight of the tax it was intended to destroy its subject. But, in the act before us, the presumption of validity cannot prevail, because the proof of the contrary is found on the very face of its provisions. Grant the validity of this law, and all that Congress would need to do, hereafter, in seeking to take over to its control any one of the great number of subjects of public interest, jurisdiction of which the States have never parted with, and which are reserved to them by the Tenth Amendment, would be to enact a detailed measure of complete regulation of the subject and enforce it by a so-called tax upon departures from it. To give such magic to the word "tax" would be to break down all constitutional limitation of the powers of Congress and completely wipe out the sovereignty of the States.
The difference between a tax and a penalty is sometimes difficult to define