Mass. Tax Revolt

The Boston Globe reports:

Swamped by angry calls and e-mails, House and Senate leaders abandoned plans yesterday to retroactively charge 48,000 taxpayers for capital gains incurred nearly four years ago and also ordered thousands of refunds to investors.

The 48,000 taxpayers sold assets in the first four months of 2002, but they began receiving bills this fall to pay taxes for those transactions at a higher rate than lawmakers enacted that year. The taxpayers can now ignore the bills, lawmakers said.

Aren't "retroactive things" supposed to be unconstitutional?