Why did thomas jefferson approve of the louisiana purchase

Read the passage from the opinion of the court in dred scott v. sandford, written by justice taney. the question then arises, whether the provisions of the constitution, in relation to the personal rights and privileges to which the citizen of a state should be entitled, embraced the negro african race, at that time in this country, or who might afterwards be imported, who had then or should afterwards be made free in any state; and to put it in the power of a single state to make him a citizen of the united states, and endue him with the full rights of citizenship in every other state without their consent? does the constitution of the united states act upon him whenever he shall be made free under the laws of a state, and raised there to the rank of a citizen, and immediately clothe him with all the privileges of a citizen in every other state, and in its own courts? the court thinks the affirmative of these propositions cannot be maintained. and if it cannot, the plaintiff in error could not be a citizen of the state of missouri, within the meaning of the constitution of the united states, and, consequently, was not entitled to sue in its courts. what claim does justice taney make in this passage? that sanford has the right to enslave scott that scott has the right to be emancipated that scott is not a citizen of missouri that sanford cannot sue because he is not a citizen