Arbitrator Mackensen resigned from the Arbitration Committee on Sunday, citing personal reasons.

Mackensen blanked his user page on 19 February. Arbitrator Raul654 removed Mackensen from the Committee member list, the first public notification of his resignation. A day later, Mackensen clarified his actions, saying "...I resigned this post on February 19, 2006. My reasons for doing so are my own, and I am not willing at the moment to revisit what was for me a painful, if necessary, decision."

This followed his recent involvement in the ongoing dispute over userboxes, which continues to cause problems despite an Arbitration Committee ruling and repeated urgings from Jimbo Wales for cultural change to discourage the more objectionable uses. The latest episode involved a number of userboxes being deleted under the new speedy deletion criterion for templates, especially the explicitly political type which Wales had criticized. Mackensen had been one of several administrators involved in deleting these. A few of these were restored by Guanaco after being debated on Wikipedia:Deletion review, and that forum has now become a focus of attention, to the point that the discussion has been split off to a separate subpage.

It is unknown how soon the post vacated by Mackensen will be filled. Jimbo Wales had left open the possibility to appoint new Arbitrators from a pool of highly supported candidates from the last election; however, it's not clear whether Jimbo will choose to do so right away, or to appoint candidates after more leave the committee, as he did in July and October 2005.

Mackensen's resignation brings the Committee's active membership to twelve members, down from the fifteen members on the Committee after Jimbo appointed new Arbitrators in January. Filiocht is listed as inactive, and due to illness has not taken any Arbitration-related actions since his appointment. Additionally, Sam Korn is currently on vacation.