The verdict in this case must be set aside, tor the reason that the instruction of the court below, that the burden of proof, as to the excess of force used on the plaintiff, was erroneous. The defendant having obtained the opening and close, took upon himself the burden of proof, to justify all he did, to make out a good justification throughout. Such was the decision in the case of Hannen v. Edes, 15 Mass. 347, under the old system of pleading, and on technical grounds. But here the case is much stronger, because the defendant voluntarily assumes the general burden of making out a full justification of all he did, and for that purpose obtained the right to open and close.