1. Heresy was never established as a crime in Geneva. The crime of Blasphemy (not to be confused with Heresy) had always been punished with exile in Geneva.
2. Calvin, when the Catholics had power, argued heresy was not a death penalty offense (Institutes). After killing Servetus, Calvin reversed his stance (Defense of the orthodox faith in the sacred Trinity), and edited out of new editions of the Institutes his earlier position.
3. Calvin’s companion, Castellio was horrified at Calvin’s bloodlust against Servetus. Castellio argued the above points, plus Castellio argued for a principle of free speech.
4. Servetus did not write or speak in Geneva and therefor broke no laws of Geneva. He was a visitor, punished for thought crimes.
5. Calvin bragged about executing Servetus in his Defense of the Orthodox Faith and in a letters to Marquis Paet.
6. Before Servetus was murdered, Calvin wrote to Farel and Viret his intentions to kill Servetus.
7. Calvin had god-like power in Geneva. In 1552, the Senate of Geneva decreed the Institutes were “God’s doctrine”.
8. Testifying to his power in Geneva, Calvin also personally had revised the Civil Code of Geneva and also the Geneva Confession of Faith (1536).
9. The court (laymen led town counsel) originally was only considering exiling Servetus, until Calvin appeared in court. Calvin convinced them to increase the penalty to death, more than the maximum that the blasphemy laws allowed.
10. Calvin personally argued to the layman court, that the Bible condoned putting Servetus to death.
11. Calvin also ensured Servetus would be denied legal counsel.
12. Calvin ensured Servetus’ request for appeal be denied, and thus denied Servetus’ case to be heard by lawyers.