Compare the Confederate and US Constitutions. One barred the importation of slaves, the other prohibited a bar on the importation of slaves:
Confederate Constitution:
Sec. 9. (I) The importation of negroes of the African race from any foreign country other than the slaveholding States or Territories of the United States of America, is hereby forbidden; and Congress is required to pass such laws as shall effectually prevent the same.
(2) Congress shall also have power to prohibit the introduction of slaves from any State not a member of, or Territory not belonging to, this Confederacy.
US Constitution:
Section 9.
The migration or importation of such persons as any of the states now existing shall think proper to admit, shall not be prohibited by the Congress prior to the year one thousand eight hundred and eight, but a tax or duty may be imposed on such importation, not exceeding ten dollars for each person.
How do you interpret that as "barring slave imports" when it specifically says imports from the U.S. are allowed?