Engel, C. (2001). The Constitutional Court – Applying the Proportionality Principle – as a Subsidiary Authority for the Assessment of Political Outcomes. Bonn: Max Planck Institute for Research on Collective Goods

Engel, C. (2001). The European Charter of Fundamental Rights: A Changed Political Opportunity Structure and its Dogmatic Consequences. Bonn: Max Planck Institute for Research on Collective Goods

Engel, C. (2001). Hybrid Governance Across National Jurisdictions as a Challenge to Constitutional Law. Bonn: Max Planck Institute for Research on Collective Goods

Engel, C. (2001). Rechtliche Entscheidungen unter Unsicherheit. Bonn: Max Planck Institute for Research on Collective Goods

Engel, C. (2001). A Constitutional Framework for Private Governance. Bonn: Max Planck Institute for Research on Collective Goods

Engel, C. (2000). Delineating the Proper Scope of Government - a Proper Task for a Constitutional Court? Bonn: Max Planck Institute for Research on Collective Goods

Engel, C. (2000). Die Grammatik des Rechts - Funktionen der rechtlichen Instrumente des Umweltschutzes im Verbund mit ökonomischen und politischen Instrumenten. Bonn: Max Planck Institute for Research on Collective Goods

Engel, C. (2000). Offene Gemeinwohldefinitionen. Bonn: Max Planck Institute for Research on Collective Goods

Engel, C. (1999). Institutionen zwischen Staat und Markt. Bonn: Max Planck Institute for Research on Collective Goods

Engel, C. (1999). The Internet and the Nation State. Bonn: Max Planck Institute for Research on Collective Goods

Engel, C. (1999). Vertrauen: ein Versuch. Bonn: Max Planck Institute for Research on Collective Goods

Engel, C. (1998). Die privatnützige Enteignung als Steuerungsinstrument. Bonn: Max Planck Institute for Research on Collective Goods

Engel, C. (1998). Rechtswissenschaft als angewandte Sozialwissenschaft. Bonn: Max Planck Institute for Research on Collective Goods, Discussion Paper 1998/1

Engel, C. (1998). Selbstregulierung im Bereich der Produktverantwortung. Instrumente und deren Ausgestaltung. Bonn: Max Planck Institute for Research on Collective Goods