If the amount for the consultant is modest, say, less than $3,000, we
let the PI engage the consultant as a consultant on a consultant
contract.  If the amount gets much larger, we ask--tell--the PI to make
the person a collaborator and contract with his or her employer--unless
the PI can come up with a letter from the consultant's boss that
approves the proposed work.  Most unviersities have policies that define
the amount of consulting a faculty member can do, usually by number of
days rather than amount of money.  But when one of our PIs proposes to
pay, say, $9,000 directly to a faculty member at another university, one
wonders whether the consulting job will conflict with the consultants
obligation to her employer or, conversely, whether a full--time academic
really has enough time to devote $9000 worth of work to the project
here.
--
Peter J. Dolce, Ph.D., Director
Office of Research Support Services
Meharry Medical College
Nashville, TN  37208
P (615) 327 6703
F (615) 327 6738