certifiably

Was the accused at the time of the commission of the act with which he is charged, and before that time, laboring under such mental disease as to render him certifiably insane? […] He goes on to ask, How is a jury to determine whether a man is " certifiably insane?" How is any man to attach a definite meaning to "certifiably insane?" "The phrase can only mean that a couple of doctors can be found to certify that in their opinion the man is insane."

The main purpose for California Certified Organic Farmers is to certify that the products that growers are selling are certifiably organic

He is certifiably nuts

The Tofu Cheesecake Bake-Off, which ten daring bakers had entered, was a special event held mid-week. It was, certifiably, the world's first such tofu pie contest