He published works on a variety of topics in Czech, German, French and English, focusing especially on private and transportation law issues.

[1] Before Mandl reached his fourteenth birthday, he is said to have built his first Blériot-type monoplane and thus showed a keen interest into modern transportation from an early age.

In 1925, he authored a paper on evidence for the congress of Czechoslovak lawyers and in 1926, he penned a self-published monograph on Czechoslovakian marriage law.

[4] His thesis was unanimously approved and his test lecture on the liability of contractors for damage was held successfully on 30 April 1930; the Czechoslovak minister of education then confirmed him[a] as a Privatdozent on 30 September 1932 with a venia legendi for the law of industrial enterprises.

It dealt, inter alia, with the works of Konstantin Tsiolkovski, Robert H. Goddard, Franz von Hoefft and Hermann Oberth on rocketry and contained a description of Mandl's own patent for a rocket,[b] which was granted in Czechoslovakia in 1933.

Only twenty-five copies of the work were eventually sold,[11] but this monograph is now remembered – and praised – as the first stand-alone volume on space law.

[10] In this part he deals with overflight rights over real property, he strongly argues for the application of strict liability, and he considers the sovereignty of states over their airspace.

[10] In his deliberations about future developments, he foresees the legislators becoming active in this field of law and argues for licencing of space flights and the application of strict liability.

[14] The final passage of Mandl's considerations on the future discusses the implications of regular spaceflight and the colonization of new worlds on statehood and national sovereignty.

[15] Es ist unschwer einzusehen, daß es nicht möglich sein wird, den juristischen Staats- und Rechtsbegriff von heute aufrechtzuerhalten, sobald die Erschließung des Weltraumes den Erdbewohnern neue hoheitlose Gegenden eröffnet, und daß daher der Aufschwung der Raumfahrt zugleich eine neue Epoche in der Geschichte jener beiden Begriffe – des Staates und des Rechts – bedeuten wird.

It is easy to see that it will not be possible to maintain today's legal concepts of state and law as soon as the opening up of outer space provides new areas without sovereignty for the inhabitants of earth, and that therefore the upswing of space travel will at the same time signify a new epoch in the history of those two concepts – of state and of law.

[19] According to research by Michal Plavec of the National Technical Museum (Prague), Mandl held strong antisemitic views.

[9] Mandl contracted tuberculosis and stayed in a sanatorium in Nová Ves pod Pleší (Příbram district) in 1940.

Sind solche noch gar nicht sichtbar oder steht in keiner Weise fest, wie sie in Erscheinung treten werden, so darf sich der Jurist als solcher mit ihnen nicht befassen, geschweige denn etwa der Gesetzgeber an ihre Regelung herantreten.