Michael Servetus was a wandering Aragonese at a time dominated by the religious fights initially brought about by the Lutheran Reform. Servetus shook the underpinnings of the Christian faith of his time with his antitrinitarian and anabaptist doctrines. As Erasmus of Rotterdam (see his Praise of Madness), but from a more radial position, Servetus also criticized the corruption in the Church and proposed a return to the roots and purity of Christianity. Servetus, however, was not condemned for his criticisms of the Church, but mostly for his opposition to the Nicaean interpretation of the doctrine of the Trinity and his rejection to infants' baptism.

Servetus’ theory makes Jesus Christ a kind of prophet, and in this way brings Christianity closer to Islam and Judaism. The doctrine of the Trinity was one of the dogmas in which Catholics, Protestants and Calvinists agreed upon. For this reason, any attack on this dogma was considered a serious offence in the civil and ecclesiastical jurisdictions of practically all Christian Europe.

Indeed, before being prosecuted in Geneva, Servetus was persecuted and condemned to be burnt at the stake by the French Inquisition in Vienne Dauphiné (France). On July 7, 1553, Servetus fled from the prison in which he had been confined. Since they could not burn him in person, the sentence was executed by burning an effigy of Servetus along with his some of his heretic books.

On August 22, 1553, Servetus addressed a writ to the Minor Council of Geneva, the competent body to judge him, and asked the Council to dismiss the criminal accusation. Servetus argued in his defense that the doctrine which advocated the death penalty for interpreting the Scriptures incorrectly was not embedded in the doctrine of the Apostles and the disciples of the first Church. In the same writ, Servetus requested a lawyer to assist him. The General Prosecutor refused against both requests. The reason given by the public prosecutor for turning down Servetus’ request for legal assistance was that, since Servetus was able knew to lie so well, he was smart enough to defend himself.

The discussion relating to the origin of the criminal accusations lying in differences in the interpretation of Scriptures was less frivolous. Servetus argued that during the first centuries of the existence of Christianity, the Church tried to solve its internal differences by means of peaceful discussion. This situation began to change when Christianity became the official religion of the Roman Empire as a result of the Constantinus Edict (313). Although the Council of Nicaea (325) had already condemned the antitrinitarian approach of Arrius. Religious heresy was not criminalized until the reign of Emperor Teodosius the Great (379-395).

The Code of Teodosius was completed by the Code of Justinianus (527-534). This latter Code, which was in force in the territories of the Sacred Roman Empire, prescribed in the chapter "Of summa catholica Trinitate et fide, hereticis, apostatis" the capital punishment for those negating the doctrine of the Trinity and the baptism of infants. The Code of Justinianus could have constituted the legal basis to issue the judgment against Servetus. In fact, the Genevan judges asked Servetus if he knew of the existence of this legal text. Servetus replied that he did know of the existence, but that, in any case, its existence did not invalidate his arguments, since Justinianus did not belong to the primitive Church, but rather to an era in which “the bishops commenced their tyranny, and criminal accusations have been introduced in the Church”. The Code of Justinianus, however, did not serve as the legal basis of the judgment against Servetus, since all Canon laws had been abolished by the Genevan reformers. Therefore, the question which arises still is: what was the legal basis which allowed the judges in Geneva to condemn Servetus?.

On October 26 of 1553, the Council issued its judgement against Servetus ordering him to be burnt alive in the hill of Champel. The judgment stated that Servetus was guilty for having printed "twenty-three or twenty-four" years ago a book (“De Trinitatis Erroribus”) that contained blasphemies against the Trinity and for having corrupted Christians and spread his antitrinitarian heresy in a later work (“Christianismi Restitutio”). Furthermore, the judgment condemned Servetus for opposing the baptism of infants. It must be noted that the Genevan judges appear to have intentionally erred in the qualification of the charges against Servetus. From the records of the trial and the reasoning of the judgment it cannot be inferred that the crime of which Servetus was being accused had been committed in the territory of Geneva.

Applying the most elementary principles of Criminal Law, the judges should have acquitted Servetus, or simply found him guilty of attempting to commit that crime and, consequently, they should have applied a less rigorous penalty such as banishment. Finally, it is also surprising that Servetus’ request to have his case brought before the Council of the Two Hundred (a body in charge of legislating in Geneva and of electing the 25 members of the Small Council) was ignored by the Genevan magistrates. This decision of the judges, along with their refusal to allow Servetus to be assisted by a lawyer, is another example of the irregularities that vitiated the process against Servetus and demonstrate the scarce legal rigor of the Genevan court, most likely due to the strong influence that Calvin exerted upon the judges.