B.S.! Your comparision is false on its face.
Just where is slavery mentioned? Show me. No nods and winks, I mean the incorporation of slavery as a practice enumerated in the U.S. Constitution.
Show me! I'm waiting.
"Provided that no Amendment which may be made prior to the Year One thousand eight hundred and eight shall in any Manner affect the first and fourth Clauses in the Ninth Section of the first Article" - Article V
"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." - Article I, Section 9.1
"No Person held to Service or Labour in one State, under the Laws thereof, escaping into another, shall, in Consequence of any Law or Regulation therein, be discharged from such Service or Labour, but shall be delivered up on Claim of the Party to whom such Service or Labour may be due." - Article IV, Section 2.3