The event of Chicago Mercantile Exchange’s (CME) negative oil clearing price on April 20, 2020, in which commodity futures traded in a negative range, is significant to the financial community worldwide. Through discussions of the so-called “best practice” rule for professional behaviors in practice with a number of examples and standards established by professional organizations, it seems that a better option for CME’s execution would have been to first seek feedback from stakeholders internationally within a reasonable transition period before implementing the proposed new trading (or updating) rule that came into effect in the month of April 2020.