Was the 16th amendment ratified?
There is a lot of debate over whether the 16th amendment was ratified, but the question itself is irrelevant. The Supreme Court has ruled several times that the 16th amendment changed nothing. In Brushaber v Union Pacific (https://supreme.justia.com/cases/federal/us/240/1/) Peck and Co v Lowe (https://supreme.justia.com/cases/federal/us/247/165/) and Stanton v Baltic Mining (https://supreme.justia.com/cases/federal/us/240/103/).
In Stanton v Baltic Mining:
“But, aside from the obvious error of the proposition, intrinsically considered, it manifestly disregards the fact that, by the previous ruling, it was settled that the provisions of the Sixteenth Amendment conferred no new power of taxation, but simply prohibited the previous complete and plenary power of income taxation possessed by Congress from the beginning from being taken out of the category of indirect taxation to which it inherently belonged, and being placed in the category of direct taxation subject to apportionment by a consideration of the sources from which the income was derived — that is, by testing the tax not by what it was, a tax on income, but by a mistaken theory deduced from the origin or source of the income taxed.”
So what they are saying here is that the 16th amendment does not grant a new power to tax income, in fact it claims that they had that power all along. The previous income tax from the Civil War was ruled unconstitutional in 1895, not because it was a tax on income, but because it was a direct tax. The 16th amendment does not remove that prohibition, but the court ruled that it limited it even further, by saying that an income tax can ONLY be taxed as an excise, not as a direct tax, regardless of apportionment.
There was a case brought by a veteran suing the government over an illegal war in which case the judge stated that he believed the 16th amendment had not been ratified, but this was not part of the ruling and does not stand as fact.