[CryptoPunk]

The income tax was first introduced in the UK, in 1799, to fund a war against France, and the rate was only 10%, and only levied on the rich.

The first American income tax was also introduced in a war - the Civil War.

[jackfoxy]

IIRC the US Supreme Court declared the Civil War era income tax unconstitutional, which is why it required a constitutional amendment.

[bluGill]

No, they said the tax on capital gains was unconstitutional. An income tax itself was allowed, they only tossed out the whole law because it was obvious that the tax code they ruled unconstitutional wouldn't make sense without the capital gains tax parts.