No penalty without a prior published law, so power must bind itself before it acts.
Feuerbach's 1801 formulation, and the principle behind prohibitions on retroactive criminal law. It requires power to bind itself before acting, which is what distinguishes law from decree.
In practice
- A regulator that fines a firm under a standard published after the conduct has punished without a rule.
- An employer that dismisses for breaching a policy issued last week, for conduct from last year, has done the same thing.
- Further reading
- Wikipedia
- Subject
- Law & Politics
- Essay
- Rules that restrain power, and advice on using it