There had been no law authorizing execution for such a crime previously and using this new one against van der Lubbe violates the long-standing legal maxim nulla poena sine legal (no punishment without law). Adolf Hitler, however, is only interested in results, not following the law.
Reich Minster of Justice Franz Gürtner declares that the new law, infamously known as the Lex van der Lubbe, is necessary for Germany's war against "international terrorism."
With this, the entire justice system places itself at the beck and call the Nazi leadership; judicial decisions are made on the basis of what Hitler wants and the presumed needs of the German people rather than abstract notions of justice, law, or fairness.
Ignoring traditional legal standards in order to achieve a pre-determined goal will become a standard feature of the Nazi regime, something that makes it easier for them to disenfranchise and then later start killing Jews.