In November 2012, McCallum began creating a body of portraits depicting defendants standing trial before international courts titled Weights and Measures.
[12] McCallum has completed painted portraits of Thomas Lubanga, Slobodan Milošević, Radovan Karadžić, Germain Katanga, Kang Kek Iew, Nuon Chea, William Ruto, Charles Taylor, Jean-Pierre Bemba, and Fidèle Wandu.
[13] The city is both the site of the original manufacturing plants of the Colt family, which were important to its economy and, because of issues related to current poverty and drug use, has suffered some of the highest rates of gun-related deaths in the United States.
McCallum emblazoned each manhole cover with the words "MADE FROM 172 LBS OF YOUR CONFISCATED GUNS" and the common epitaph "VINCIT QUI PATITUR," which roughly translated can mean either "he who perseveres is victorious" or "he who suffers conquers.
[5] McCallum curated the first exhibition for the Arts Initiative, a travelling group show titled Post Conflict that included work by prominent artists Ai Weiwei, Richard Mosse, Alfredo Jaar, Jenny Holzer, Adam Pendleton, Pieter Hugo, Lana Mesic, Daapo Reo, and a selection of African cartoonists by Creative Court.