Since the states that would form the CSA effectively seceded (to my knowledge) over their concerns that the US government might at some point act to put an end to slavery in the South, I was rather surprised to come across the following section in their 1861 constitution:
Article 1, Section 9, Clause(?) 1: 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.
Clause(?) 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.
I don't know whether the CSA actually acted upon this, but I'm confused as to why they would have maintained the ban on the trans-Atlantic slave trade the USA had implemented before the outbreak of the Civil War, given that access to the still-existing slave trade might have been an economic boon for Southern plantation owners. I can't imagine the ban would have been for humanitarian reasons, given the Confederate insistence on maintaining slavery itself as an institution. Were the seceding states afraid of rousing hostility from abolitionist Britain or the North?
EDIT: added second clause(?) I'm not American, so I have no idea what these are called.
A similar question was posted not too long ago, and I addressed this question, more or less, in that previous answer.
The second clause you cited was put in there as a coercive measure to try to get the slave states loyal to the Union to secede (either now or in the future). Parts of the U.S. where slavery remained legal would be forbidden from bringing enslaved people into the Confederacy. However, if those states joined the Confederacy, then slavery in those states would be secure and broadly protected. The ploy didn't really work. Although, maybe it kind of did. At the time the Confederate constitution was adopted, Virginia, North Carolina, Tennessee, and Arkansas hadn't yet seceded. Then again, none of them ever cited this clause as a particular motivating factor in secession.