I have a polygon face randomly rotated.

All the attributes have been zeroed out due to a freeze transform operation.

I would like to rotate the face perpendicular to an orthogonal view while retaining the exact shape of the face.

Is there a way to achieve this operation without just eyeballing it while rotating?

Is there a Mel script?

Yes, take the edge you want in either y and x and the surfaces normal, take their cross product. THis form a matrix out of theese 3 vectors this can be decomposed to rotations. Incidenttaly this is what  constraints do so just inject face normal to along and edge vector to aim of a rotate constraint for example.

Also the snap align tools in the modify menus do just this asevell as snap together tool. Just make a extra plane or  align to the construction plane, this is probably the least hastle.

Thank you very much Joojaa. This does exactly what I wanted.