They certainly have the power to collect the tax money required, and the Social Security SCOTUS case(Helvering v. Davis) sets a pretty good starting point for t

They certainly have the power to collect the tax money required, and the Social Security SCOTUS case(Helvering v. Davis) sets a pretty good starting point for their power to spend. I'd argue that while they have the power to spend the money on a wide variety of social programs(per the General Welfare clause), they don't have the power to redistribute income since it doesn't have a designated purpose. Spending is an exchange of money for services or goods, while UBI would just be an exchange of money. Even if redistribution was considered a type of spending, the case mentions specific facts that harmed the elderly(employee age limits being the main one). If these mattered to the original case, then giving UBI to young people who choose not to work should be a weaker case, which makes it reasonable for SCOTUS to disagree at least on those examples. Social Security is a combination of a forced retirement savings plan and a delayed redistribution of income. I don't know if anyone has argued that the redistribution part alone is unconstitutional, but the forced savings part comes from the payout increasing as you put more money in. A UBI would be entirely a redistribution. A similar argument might apply to cases where the EITC causes a net benefit to be given to someone, but: A. The government could argue that the EITC is intended to benefit the poor, which seems similar to arguing that Social Security benefits the elderly and B. I don't know if anyone has standing to bring a suit, since those cases are probably rare and the damages would be small.