rt, by the plea that the plaintiff was a negro of
African blood, the descendant of Africans who had been imported and
sold in this country as slaves, and thus he had no capacity as a
citizen of Missouri to maintain a suit in the Circuit Court. The court
sustained a demurrer to this plea, a trial was then had upon the
general issue, and special pleas to the effect that the plaintiff and
his family were slaves belonging to the defendant.

My opinion in this case is not affected by the plea to the
jurisdiction, and I shall not discuss the questions it suggests. The
claim of the plaintiff to freedom depends upon the effect to be given
to his absence from Missouri, in company with his master, in Illinois
and Minnesota, and this effect is to be ascertained by a reference to
the laws of Missouri. For the trespass complained of was committed
upon one claiming to be a freeman and a citizen, in that State, and
who had been living for years under the dominion of its laws. And the
rule is, that whatever is a justification where the thing is done,
must be a justification in the forum where the case is tried. (20 How.
St. Tri., 234; Cowp. S.C., 161.)

The Constitution of Missouri recognises slavery as a legal condition,
extends guaranties to the masters of slaves, and invites immigrants
to introduce them, as property, by a promise of protection. The laws
of the State charge the master with the custody of the slave, and
provide for the maintenance and security of their relation.

The Federal Constitution and the acts of Congress provide for the
return of escaping slaves within the limits of the Union. No removal
of the slave beyond the limits of the State, against the consent of
the master, nor residence there in another condition, would be
regarded as an effective manumission by the courts of Missouri, upon
his return to the State. "Sicut liberis captis status restituitur sic
servus domino." Nor can the master emancipate the slave within the
State, except through the agency of a public authority. The inquiry
arises, whether the manumission of the slave is effected by his
removal, with the consent of the master, to a community where the law
of slavery does not exist, in a case where neither the master nor
slave discloses a purpose to remain permanently, and where both
parties have continued to maintain their existing relations. What is
the law of Missouri in such a case? Similar inquiries have arisen in a
great number of suits, and