In follow-up to Question 31:
Q32. "I didn't find myself enlightened by the answer.... Perhaps a better way to phrase the question would be, why couldn't an income tax be levied without the 16th amendment? I know that Congress tried to pass an income tax before the 16th amendment but the Supreme Court struck it down. What was the Supreme Court's rationale for doing so? If, as the FAQ says 'the 16th Amendment authorizes the Congress to lay and collect a tax on any income,' what kinds of income could they tax before, and what part of the Constitution so limits them?"
A. The question, then, is WHY was it was needed. The issue is not that the Constitution otherwise forbids an income tax, but that it does not otherwise permit one. Without an amendment to specifically state that an income tax was constitutional, any income tax proposed by the Congress would be subject to judicial review, and possible overturning by the Court; and then who knows what kind of chaos that would cause. Say the government levied an income tax in 1910, and in 1913 the Court determined the tax was unconstitutional. It is not outside the realm of possibility that the Court would order all collected funds be returned to the people. Yikes!
In 1895, the Court ruled that a tax from income derived from property was unconstitutional based on Article 1, Section 9, Clause 4. If you read that, you'll see that it is unclear how this makes an income tax unconstitutional, but the Court sometimes deals in legal technicalities, and this technicality divided the court 5-4 against the tax. The amendment was ratified 18 years later, and prevented such cases from ever needing to appear in court.