Is American Community Survey required by law?

The previous author of the answer states it is not an invasion of privacy, yet attempts to justify this invasion by suggesting it will help the community. This survey should be voluntary, yet on the envelope it states it is required by law and you could get fined if you don't answer. See below on the true legality of the ACS:

Pursuant to Article I, Section 2, Clause 3 of the Constitution, the only information the census bureau are empowered to request is the total number of occupants at this address. My "name, sex, age, date of birth, race, ethnicity, telephone number, relationship and housing tenure" have absolutely nothing to do with apportioning direct taxes or determining the number of representatives in the House of Representatives. Therefore, neither Congress nor the Census Bureau have the constitutional authority to make that information request a component of the enumeration outlined in Article I, Section 2, Clause 3. In addition, I cannot be subject to a fine for basing my conduct on the Constitution because that document trumps laws passed by Congress.

Interstate Commerce Commission v. Brimson, 154 U.S. 447, 479 (May 26, 1894)

"Neither branch of the legislative department [House of Representatives or Senate], still less any merely administrative body [such as the Census Bureau], established by congress, possesses, or can be invested with, a general power of making inquiry into the private affairs of the citizen. Kilbourn v. Thompson, 103 U.S. 168, 190. We said in Boyd v. U.S., 116 U. S. 616, 630, 6 Sup. Ct. 524,―and it cannot be too often repeated,―that the principles that embody the essence of constitutional liberty and security forbid all invasions on the part of government and it's employees of the sanctity of a man's home and the privacies of his life. As said by Mr. Justice Field in Re Pacific Ry. Commission, 32 Fed. 241, 250, 'of all the rights of the citizen, few are of greater importance or more essential to his peace and happiness than the right of personal security, and that involves, not merely protection of his person from assault, but exemption of his private affairs, books, and papers from inspection and scrutiny of others. Without the enjoyment of this right, all others would lose half their value.'"

Note: This United States Supreme Court case has never been overturned.