How did the Constitution allow slavery?

Slavery was implicitly recognised in the original Constitution in provisions such as Article I, Section 2, Clause 3, commonly known as the Three-Fifths Compromise, which provided that three-fifths of each state's enslaved population (“other persons”) was to be added to its free population for the purposes of apportioning seats in the United States House of Representatives and direct taxes among the states.

The original Constitution forbade Congress from establishing legislation against slaves until 1808, 21 years after the first Constitution was signed.

Explanation: Another agreement was reached between constitutional Congress representatives who supported and opposed the slave trade.

hope this helps good luck mate! :)

no every country is held to the same degree as others just some member countries such as the usa and germany are more economically sound so the need to show there support to all others