let the fox guard the henhouse —(also: set the fox to keep the geese) trust a person with smth. that he is especially likely to misappropriate or abuse:
- Back in 1951, members of the State Department wrote the text of the treaty. Now different people in the State Department are trying to define what was written. I don’t believe we should let the fox guard the henhouse.
put the cat among the pigeons —(also: set the cat among the pigeons) do or say smth. that is bound to cause trouble and make people angry:
- I put the cat among the pigeons by recommending that revalidation should include the provision of a certificate that the doctor has passed a knowledge test at some stage in the five year period.