Ind. Code § 35-35-1-3
(c) A plea of guilty or guilty but mentally ill at the time of the crime shall not be deemed to be involuntary under subsection (a) solely because it is the product of an agreement between the prosecution and the defense.
As added by Acts 1981, P.L.298, SEC.4. Amended by P.L.320-1983, SEC.16; P.L.179-1984, SEC.2.