A hurried or impetuous decision or finding, as in George was known for making snap judgments on personnel questions; he rarely bothered to investigate further. This expression, which uses snap in the sense of “quick,” was first recorded in 1841.
Examples from the Web for snap judgment
This would be what is vulgarly called a snap-judgment indeed.
The world may not know but these snap-judgment profiteers, these get-rich-quick phenomena, always have to pay.The Gorgeous Girl