rein — as in: to rein in their activities
The court reined in agency power—describing it as out of control.
to restrain or control as in "rein a horse"; or a means of control — such as the reins of a horse or of government
(The reins of a horse are the pair of straps attached to a bit in a horse’s mouth and used to control it.)
To "rein in" or to "keep a tight rein" is to restrain.
To "give free rein" is not to restrain (not to exercise control over)