YES – Kingdom Ministry 9/77 p. 6 par. 37 New Arrangements for Congregation Organization
If a congregation is in an isolated area and it is not convenient to have elders from a distant place sit with the local judicial committee members, then a well-qualified ministerial servant may be selected to complete the judicial committee.
NO – Letter to Body of Elders July 11th 2014 (7/11/14E)
Ministerial servants should not be used to serve on judicial committees.