CGC's Policy on Approving Sig Series Venues and Witnesses, Thoughts? in The Signature Room Posted April 14, 2016 I know that CGC also put a firm ban on people witnessing their own books, Since when? 2010 Yup. https://www.cgccomics.com/news/viewarticle.aspx?IDArticle=1484& I was hoping to see CGC institute a booth-based breathalyzer or THC test for witnesses. The last thing we'd need are impaired witnesses, not that anything like that is likely.