A surgical stapler comprising: (a) a body; (b) a shaft assembly extending distally from the body; (c) an end effector at a distal end of the shaft assembly, wherein the end effector is actuatable between an open state for receiving tissue and a closed state for clamping the tissue; (d) a closure system operatively coupled with the end effector, wherein the closure system is operable to actuate the end effector from the open state to the closed state; (e) a firing system operatively coupled with the end effector, wherein the firing system is operable to actuate the end effector in the closed state to staple the clamped tissue; and (f) a firing lockout mechanism operatively coupled with the firing system, wherein the firing lockout mechanism is movable between a lockout state in which the firing lockout mechanism inhibits actuation of the firing system, and a bypass state in which the firing lockout mechanism permits actuation of the firing system, wherein the firing lockout mechanism is configured to maintain the lockout state until the end effector assumes the closed state, wherein the firing lockout mechanism is configured to transition from the lockout state to the bypass state in response to the end effector assuming the closed state; wherein the firing lockout mechanism comprises: (i) a first moveable member, and (ii) a second movable member operatively coupled with the first movable member, wherein the second moveable member is configured to engage and thereby inhibit actuation of the firing system in the lockout state, wherein in response to the end effector assuming the closed state, the first moveable member is configured to drive the second movable member out of engagement with the firing system and thereby provide the firing lockout mechanism in the bypass state, and characterised in that the first moveable member is configured to translate along a first axis, wherein the second moveable member is configured to translate along a second axis that is perpendicular to the first axis. (a) a body; (b) a shaft assembly extending distally from the body; (c) an end effector at a distal end of the shaft assembly, wherein the end effector is actuatable between an open state for receiving tissue and a closed state for clamping the tissue; (d) a closure system operatively coupled with the end effector, wherein the closure system is operable to actuate the end effector from the open state to the closed state; (e) a firing system operatively coupled with the end effector, wherein the firing system is operable to actuate the end effector in the closed state to staple the clamped tissue; and (f) a firing lockout mechanism operatively coupled with the firing system, wherein the firing lockout mechanism is movable between a lockout state in which the firing lockout mechanism inhibits actuation of the firing system, and a bypass state in which the firing lockout mechanism permits actuation of the firing system, wherein the firing lockout mechanism is configured to maintain the lockout state until the end effector assumes the closed state, wherein the firing lockout mechanism is configured to transition from the lockout state to the bypass state in response to the end effector assuming the closed state; wherein the firing lockout mechanism comprises: (i) a first moveable member, and (ii) a second movable member operatively coupled with the first movable member, wherein the second moveable member is configured to engage and thereby inhibit actuation of the firing system in the lockout state, wherein in response to the end effector assuming the closed state, the first moveable member is configured to drive the second movable member out of engagement with the firing system and thereby provide the firing lockout mechanism in the bypass state, and characterised in that the first moveable member is configured to translate along a first axis, wherein the second moveable member is configured to translate along a second axis that is perpendicular to the first axis. wherein the firing lockout mechanism is configured to maintain the lockout state until the end effector assumes the closed state, wherein the firing lockout mechanism is configured to transition from the lockout state to the bypass state in response to the end effector assuming the closed state; wherein the firing lockout mechanism comprises: (i) a first moveable member, and (ii) a second movable member operatively coupled with the first movable member, wherein the second moveable member is configured to engage and thereby inhibit actuation of the firing system in the lockout state, (i) a first moveable member, and (ii) a second movable member operatively coupled with the first movable member, wherein in response to the end effector assuming the closed state, the first moveable member is configured to drive the second movable member out of engagement with the firing system and thereby provide the firing lockout mechanism in the bypass state, and characterised in that the first moveable member is configured to translate along a first axis, wherein the second moveable member is configured to translate along a second axis that is perpendicular to the first axis.