An endoscopic surgical instrument comprising: (a) a body; (b) a shaft assembly extending distally from the body, wherein the shaft assembly defines a longitudinal axis, wherein the shaft assembly has a distal end; (c) an end effector, wherein the end effector is operable to manipulate tissue; (d) an articulation joint (1034; 1134; 1234; 1334) coupling the end effector with the distal end of the shaft assembly, wherein the articulation joint (1034; 1134; 1234; 1334) is configured to permit the end effector to articulate along a first plane and thereby deflect away from the longitudinal axis of the shaft assembly; and (e) a locking assembly operable to selectively lock the angular position of the end effector relative to the longitudinal axis of the shaft assembly, wherein the locking assembly comprises: (i) a first locking member (1031; 1162; 1231; 1331) unitarily secured to the end effector, such that the first locking member (1031; 1162; 1231; 1331) is configured to move with the end effector relative to the longitudinal axis of the shaft assembly, and (ii) a second locking member (1030; 1130; 1230; 1330) operable to selectively engage the first locking member (1031; 1162; 1231; 1331) to thereby selectively lock the angular position of the end effector relative to the longitudinal axis of the shaft assembly, wherein the second locking member (1030; 1130; 1230; 1330) is movable along a second plane to selectively engage the first locking member (1031; 1162; 1231; 1331), and characterized in that the second plane is non-parallel with the first plane. (a) a body; (b) a shaft assembly extending distally from the body, wherein the shaft assembly defines a longitudinal axis, wherein the shaft assembly has a distal end; (c) an end effector, wherein the end effector is operable to manipulate tissue; (d) an articulation joint (1034; 1134; 1234; 1334) coupling the end effector with the distal end of the shaft assembly, wherein the articulation joint (1034; 1134; 1234; 1334) is configured to permit the end effector to articulate along a first plane and thereby deflect away from the longitudinal axis of the shaft assembly; and (e) a locking assembly operable to selectively lock the angular position of the end effector relative to the longitudinal axis of the shaft assembly, wherein the locking assembly comprises: (i) a first locking member (1031; 1162; 1231; 1331) unitarily secured to the end effector, such that the first locking member (1031; 1162; 1231; 1331) is configured to move with the end effector relative to the longitudinal axis of the shaft assembly, and (ii) a second locking member (1030; 1130; 1230; 1330) operable to selectively engage the first locking member (1031; 1162; 1231; 1331) to thereby selectively lock the angular position of the end effector relative to the longitudinal axis of the shaft assembly, wherein the second locking member (1030; 1130; 1230; 1330) is movable along a second plane to selectively engage the first locking member (1031; 1162; 1231; 1331), and characterized in that the second plane is non-parallel with the first plane. (i) a first locking member (1031; 1162; 1231; 1331) unitarily secured to the end effector, such that the first locking member (1031; 1162; 1231; 1331) is configured to move with the end effector relative to the longitudinal axis of the shaft assembly, and (ii) a second locking member (1030; 1130; 1230; 1330) operable to selectively engage the first locking member (1031; 1162; 1231; 1331) to thereby selectively lock the angular position of the end effector relative to the longitudinal axis of the shaft assembly,