President Trump and congressional Democrats last month pledged to commit $2 trillion in infrastructure projects over the next decade. The slight problem they face? No one has any idea how to pay for it. Neither party wants to run up more debt. Republicans are opposed to higher taxes. Democrats are opposed to spending cuts. What to do?

One idea is for the Treasury Department to remove inflation from the capital gains tax, something legal scholars believe could be done by regulation. Known as “capital gains indexing,” the idea is simple: Instead of a capital gain being defined as what an asset is sold for minus what it is bought for, it could instead be defined as what an asset is sold for minus what it is bought for plus inflation since purchase.