The ICTY Statute didn't allow for Trials in absentia and the American and Anglo-Saxon who favoured this ban compared to Cassese's European colleagues, because in continental Europe ( except in Spain) trials in absentia are allowed if basic safeguards for the accused are observed and the right to ask for a re-opening of trial is granted

Reading material, reports, memoranda, and correspondence on the circumstances a person could be tried "in absentia" includes a letter from Cassese to Prof Joseph Weiler, Harvard Law School, asking that one of his students write a piece on the rationale behind the American provisions that rule out trials in absentia. Excerpt of the book "Adjudication of Guilt" sent to Cassese in response to "The Right to be Present."
Suggestions by Cassese on the institution of such proceedings
Paper by P. Gillibert "Droit de comparaître en personne/procédures in abstentia Jurisprudence du Comité des droits de l’homme, de la Cour Européenne des Droits de l’Homme et vues de la Commission Européenne des Droits de l’homme »
Note de L. Joinet sur l’Elaboration du règlement du Tribunal International sur l’Ex Yougoslavie
Code of Criminal Procedure of the Socialist Federal Republic of Yugoslavia
Memo from Cassese to the Judges of the ICTY on trial by default, 1994
Council of Europe memo of the European Committee on Crime Problems, Committee of Experts on the Operation of the European Conventions in the Penal Field: Judgements in Absentia, 1998

English

Textual

Parts of text highlighted by Cassese