Metz is a former graduate student of the Plant and Microbial Biology department at UC Berkeley. He went on to become a post-doctoral fellow at Washington University.
Metz co-authored a letter published in Nature (March 2001) which attacked UC Berkeley researchers Ignacio Chapela and David Quists paper (also published in Nature). Chapela and Quists paper had shown GM contamination of indigenous Mexican maize, a conclusion subsequently verified by Mexican government researchers and others. Metz called Chapelas paper a 'testament to technical incompetence' and pointed out that Chapela was on the board of the Pesticide Action Network (PANNA), suggesting that 'an ideological conflict encouraged this lapse in scientific integrity'. He told the Washington Post (25 Mar 2002): 'the primary concern for many of us is that science is being abused, that the scientific process is being taken advantage of for ideological reasons.'
In March 2000 Metz collaborated on the production for AgBioWorld of a highly partisan document called 'Critical issues in agricultural biotechnology'. Metz worked with Barun Mitra of the Liberty Institute, 'a free market think tank in India', which supports the unregulated introduction of GM crops; Andrew Apel, editor of the industry newsletter, AgBiotech Reporter; and Gregory Conko of the rightwing Competitive Enterprise Institute, and co-founder of the AgBioWorld Foundation. Despite this Metz claimed in a letter to The Guardian (12 Jun 2002) that he and Conko 'have never exchanged so much as a single message with each other'. The document Metz worked on for AgBioWorld is on its website but it now omits Metz's role as scientific advisor, although the original can still be seen here.
AgBioWorld was also at the heart of the campaign to discredit Dr Chapela. Metz supported that campaign. Chapela has said that the scientific criticism of his work was also part of a vendetta by supporters of a 1998 $25m deal between biotechnology giant Novartis (now part of Syngenta) and UC Berkeley, a deal which Chapela had strongly opposed. 'Every single writer of [the Nature] letters has a direct link to the Novartis-Berkeley deal, every single one,' Chapela has said. Although the deal is widely regarded as an extreme example of the alignment of a place of higher education with corporate interests, Metz in a letter to the journal Nature defended the Novartis deal as a boon for Berkeley.