Weimar was particularly concerned with German and European commercial law, and dealt with the psychological and neuro-scientific fundamentals of thinking and decision-making (see neuro-jurisprudence, neuro-administratics, neuro-cognition of decision-finding, legal psychology). His basic scientific position is set out in his work “Psychological Structures of Judicial Decision (German: Psychologische Strukturen richterlicher Entscheidung, 1969, reprinted 1996), which is considered to be a legal psychology classic.