The ACE Certificate is awarded to clinicians or organizations that meet the ACORN Criteria for Effectiveness (ACE). The certificate provides external validation that the clinician or organization has met the threshold requirements for consistency of data collection, sample size, and effect size to be "certified effective".
The idea behind the ACE Certificate comes from organic farming, where organic farmers realized that their product would have greater value in the market place if there was an external body that could "certify" their product as organic. See California Certified Organic Farmers.