Case Briefs
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Da Costa v Jones

 Author: Komal Bhati, 2nd year student at ICFAI Law School Hyderabad.

 Citation: (1778) 2 Cowp 729

Date of Decision: 1778

Bench: Lord Mansfield

Original Copy: N/A


Issues in Question:

  • Whether compensation should be awarded to the plaintiff or not?
  • Whether a wager against public policy enforceable?


Background of the case:

  • This action was brought upon a wager between the plaintiff and the defendant considering the gender of Monsieur le Chevalier D’Eon, who was appointed as a temporary French ambassador in London. Over time, he made comments that made people dubious of his true gender,  leading to many wagering contracts being made on his gender. This was one of the three actions that were brought about the same issue in early 1777.
  • On 4th October 1771, the defendant agreed to pay three hundred pounds if D’Eon proves to be female in consideration that the plaintiff pays him 75 guineas then and there.
  • The defence counsel, in this case, called the witnesses to testify that D’Eon was a man rather than trying to prove that he was not a woman which was the approach used by the defence counsel in the earlier cases regarding the same subject matter. But the witnesses produced by the defence were not able to persuade as strongly as the witnesses produced by the plaintiff persuaded that D’Eon was a woman.
  • Lord Mansfield expressed his detestation for the action bought while addressing the case but it was acknowledged that it was not an illegal contract and a verdict was due. The jury found the decision in the plaintiff’s favour, awarding damages of three hundred pounds.
  • The defence counsel moved to put a stay on the verdict. This motion was based on the objection that the plaintiff should not recover the amount as upon investigation the wager may produce indelicate evidence. The objection was overruled, for the indecency of the evidence was no objection where it is necessary for the decision of a civil or a criminal court.
  • Later, Lord Mansfield took an unconventional step by applying to the defence counsel and suggesting another ground to defend the claim, yet not raised. He suggested that the defence counsel should move to a new trial with the ground that the wager should not be enforced as it materially affects a third person. The defence counsel took the advice and filed a new trial putting forth the said ground. 
  • Plaintiff contested the ground that the wager materially affects a third person by stating that wagering on any subject until prohibited by the statutes is permitted by the law of land and the subject of this case is not prohibited by the law. It was also stated that E’Don in a dispute with another person himself produced the evidence that forms the basis of the case. Since the information is public knowledge it does not affect her (D’Eon).
  •  The defence counsel argued, that to discuss the case in the court is contra bonos mores on the grounds-

1.The case inclines to produce indelicate evidence that is not necessary for either civil or criminal justice and the parties have no interest in the judgement but of their own creation.

2.It disturbs the peace of society by ridiculing an innocent third person and infringing his private life and peace of mind. These proceedings also disturbed the peace of D’Eon’s family, close relatives, confidential friends, etc who were asked to give testimony.



  • The argument by the defence counsel that the wager should not be enforced since it materially affects a third person was received well by the jury.
  • Lord Mansfield apologised that the answer given to the objection earlier was rather hastily given and that they were not considerate enough to the nature of the action. He also apologized that the witnesses subpoenaed were not informed that they could’ve refused to testify if pleased since many of them were confidential persons, servants and other employees. Their objection would have highlighted the nature of the case.
  • Moving closer to the point, the judge pointed out that one cannot come to a court with an action of wager feeling entitled to asking answers to questions such as, whether a woman committed adultery. The court would not endure that, since it affects the person and the peace of society. So, a wager whether the child to be born will be a boy or girl hurts no one, but the present case is not only indecent but most importantly hurts a third person and shall not be endured.
  • The three other judges concurred and the stay on the previous verdict was held absolute.



  • The wager which caused all the trouble was certainly an extraordinary one. Da Costa v Jones was not the first case to have been brought on the wager whether D’Eon is a male or a female.The irony of Da costa v Jones was that despite Lord Mansfield’s frequently expressed dislike of wagers, the decision gave comfort to those wanting to enforce wagers as the wagers were prima-facie enforceable. To be invalid a wager needed to be contrary to the law of land. It wasn’t until this case, that the court took the issue of public policy arising from this wager into notice.
  • A wager about the third person could be perfectly valid in Common law. The courts do not reject the contract of parties just because it was indecorous. In Earl of March v Pigott two sons made a wager running their father’s lives against each other. The court entertained this case as it did not bring any discredit to their fathers. But this case materially affected D’Eon’s Private life and interests. It was clear by the investigation of his sex that it was not possible to illustrate the case without falling into indecency, not only was he was made a subject of ridicule but it also disturbed the peace of the society.
  • Da Costa v Jones is a testament to the difficulties faced by the judges when a law of contracts runs up against public policy. This case also highlighted that it is not just through libel and privacy actions that reputation and privacy are protected. The witnesses and third parties unduly affected by such cases rarely approach the judges.Here Lord Mansfield exhibits that it is the judge’s duty to ensure that and act on their own ,even to do so belatedly if they overlap it.

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