Connection device for connecting a conductor end (3), which has a housing (1) and, in the housing (1), a busbar portion (6), a clamping spring arrangement (4) and a rotary lever arrangement (5), wherein the clamping spring arrangement (4) can be rotated, with the aid of the rotary lever arrangement (5), from an open position into a contact position in which the conductor end (3) is contacted, wherein the rotary lever arrangement (5) has a rotary lever element (50) which is mounted in the housing (1) so as to be rotatable in or on a preferably central portion (500) and which has the axis of rotation (D2), and wherein the rotary lever element (50) has an eccentric portion (502) which has a control cam (503) along which the clamping spring arrangement (4) slides during a movement into the endcontact position, wherein the eccentric portion (502) engages by way of a guide means, such as by way of a projection or a pin (504) inserted therein or the like, into a slotted link (18) of the housing (1), and wherein a clamping and / or latching means are or is formed on the eccentric portion (502), and wherein the slotted link (18) of the housing (1) is aligned with a slotted link (60) in the busbar portion (6), in which the fixing position for the clamping and / or latching means is formed.