Which would open possibilities for hampering slavery by acts of
Congress, short of constitutional amendment. Congress has the power to
regulate interstate commerce, to levy and collect taxes, and to make
uniform bankruptcy laws. A high-school American-government student can
imagine ways to use these powers to make things harder for slavery.
What follows is inspired by Gavin Wright. See his Political Economy of
the Cotton South, and Old South--New South.
The slave-price bubble of the 1850s would pop. This in turn would
likely crash the southern banking system, a big part of whose business
was making loans against the security of slave property.
With creditors holding notes secured by depreciated property, a
form of compensated emancipation might come into view. (Consider the
housing market today.)