Jurimetrics in the Constitution

I recently wrote a text in portuguese which studies how Brazil’s Supreme Federal Court decided ex-president Lula’s habeas corpus. In the following, I translate this text to English.

Brazil’s Supreme Federal Court recently decided ex-president Lula’s habeas corpus in a tight vote of 5 for and 6 against. In such a situation, some controversy is unavoidable. One of the less sophisticated arguments is that there exists a single valid interpretation of the Constitution and, therefore, anyone who decides in the opposite direction is ill-intentioned. This text aims to show that such personal arguments cannot address the complex questions which were discussed in Lula’s trial.

The first step is to prove that interpreting the Constitution is a complex activity, which involves simultaneously considering several issues. Indeed, Brazil’s Federal Constitution has 250 articles. If all of these articles were interpreted intuitively and in isolation, contradictions would immediately ensue. For example, in the following I translate articles of the Constitution that defend the right to privacy and also public security:

  • Art. 5o, X: The intimacy, private life, honor and image of people are inviolable (…)
  • Art. 144: Public security is a duty of the State and right and responsibility of every person (…)

If the right to privacy were interpreted in isolation and with maximum comprehensiveness, then every type of security camera would be prohibited. Similarly, if public security were interpreted in isolation and with maximum comprehensiveness, then one would find a justification for an all-powerful State that spies on every action of its citizens. Contrary to these naive interpretations, most people conclude that there exists a balance between these articles. There is a middle term between security and privacy that is more beneficial than either of the naive interpretations. However, finding such a middle term is a complex and subjective question, which can be answered in many ways.

In Lula’s trial, a similar question motivated the differences between the Ministers of the Supreme Court. Each Minister defended a particular balance between articles of the Constitution. One of these articles is translated below:

  • Art. 5o, LVII: No one is guilty before the final disposal of a criminal conviction.

The right which is protected in the passage above is called presumption of innocence. In Brazil, it is possible to appeal of a criminal conviction several times. If one interprets the presumption of innocence in isolation and with maximum comprehensiveness, then punishment would only be possible after no new appeal is possible.

However, the Constitution also protects several other rights, some of which are translated below:

  • Art. 5o: (…) The State guarantees to Brazilians and foreigners living in Brazil the inviolability of the right to their lives, liberty, equality, security and private property.
  • Art. 5o, LXXVIII: The reasonable duration of trials is protected (…) a todos (…) são assegurados a razoável duração do processo (…)

There exist a large number of appeals available in Brazil and Courts have long waiting lines for judging these appeals. Hence, it is possible to argue that, if the State were to wait until all appeals were judged before punishing the defendant, then punishment would take so long that it would be almost equivalent to no punishment at all. In this case, public security would be damaged, since it depends partially on proper punishment.

The vote of each Minister searched for a different balance between the constitutional principles described above. Each position is justifiable, since such a harmonization involves a subjective judgement of the relative importance of each of the principles in each practical situation. Another interesting point is that, with few exceptions, the Ministers tend to vote consistently in favor of the same harmonization of principles. That is, they vote according to their convictions and not according to the defendant.

However, despite the validity of their votes, it can be hard to understand exactly how each Minister develops the balance of constitutional principles. How different would the facts need to be so that the Minister’s votes would change? This is a hard question because, in order to balance, it is necessary to measure . How much time must a trial take so that punishment is not efficient? How much time does it take to decide each available appeal? After what appeal is the trial so long that it compromises public security? Although there exists no single valid answer to these questions, by answering them, the judge makes the rationale of his decision even more transparent. By combining Statistics to the Law, Jurimetrics provides a new valuable tool for accomplishing this goal. In next posts, I plan to discuss some jurimetric arguments that were presented by the Ministers in this case.

Rafael B. Stern
Rafael B. Stern
Professor of Statistics

I am an Assistant Professor at the University of São Paulo. I have a B.A. in Statistics from the University of São Paulo, a B.A. in Law from Pontifícia Universidade Católica in São Paulo, and a Ph.D. in Statistics from Carnegie Mellon University. I am currently a member of the Scientific Council of the Brazilian Association of Jurimetrics, an associate investigator at NeuroMat and a member of the Order of Attorneys of Brazil.