A large amount of evidence was taken in this case bearing upon the averments in the answer of misrepresentation and fraud on the part of the complainant; and it is, in many respects conflicting. But the rules of law applicable to cases of alleged misrepresentation by a vendor with respect to property sold are well settled, and render of easy solution the questions upon which this case must turn.

The misrepresentation which will vitiate a contract of sale, and prevent a court of equity from aiding its enforcement, must not only relate to a material matter constituting an inducement to the contract, but it must relate to a matter respecting which the complaining party did not possess at hand the means of knowledge; and it must be a misrepresentation upon which he relied, and by which he was actually misled to his injury. A court of equity will not undertake, any more than a court of law, to relieve a party from the consequences of his own inattention and carelessness. Where the means of knowledge are at hand and equally available to both parties, and the subject of purchase is alike open to their inspection, if the purchaser does not avail himself of these means and opportunities, he will not be heard to say that he has been deceived by the vendor's misrepresentations. If, having eyes, he will not see matters directly before them, where no concealment is made or attempted, he will not be entitled to favorable consideration when he complains that he has suffered from his own voluntary blindness, and been misled by overconfidence in the statements of another. And the same rule obtains when the complaining party does not rely upon the misrepresentations, but seeks from other quarters means of verification of the statements made, and acts upon the information thus obtained.

Slaughter's Administrator v. Gerson/Opinion of the Court

The facts disclosed by the uncontradicted testimony of both parties bring this case clearly within the principle here stated. Previous to the execution of the contract of purchase, and with the view of examining the steamboat, the defendant went from Baltimore to New York, taking with him his son, who subsequently became captain of the boat, and two shipcarpenters, and a square to measure her draught of water. Whilst there every opportunity was given him to examine the boat with his carpenters, and a most thorough and careful examination was made by them. On two occasions they measured the draught of the boat, and they witnessed her speed by accompanying her on one of her trips. The owner went with them to the boat on their arrival in New York, and told them to look for themselves, and to go anywhere they pleased about her. If, under these circumstances, the defendant did not learn everything about her, and ascertain her true draught, it was his own fault, and it would be against the plainest principles of justice to allow him to set up, in impeachment of the validity of his contract, loose statements respecting the draught before its execution, even though they were false in point of fact.

Slaughter's Administrator v. Gerson/Opinion of the Court

In Attwood v. Small, a case which received great consideration in the House of Lords, the defendant had sold to the complainants, constituting a company of numerous persons, certain freehold and leasehold property, including mines and ironworks, and had made certain statements respecting the capabilities of the property. The purchasers, not relying upon these statements, deputed some of their directors, together with experienced agents, to ascertain the correctness of his statements. These persons examined the property and works and the accounts kept by the defendant, receiving from him and his agents every facility and aid for that purpose, and they reported that the defendant's statements were correct. Upon a bill filed to rescind the contract, on the ground of fraud, the House of Lords decided that the contract could not be rescinded, reversing, in that respect, the decree of the Court of Exchequer, not merely because there was no proof of fraud, but because the purchasers did not rely upon the vendor's statements, but tested their accuracy; and, after having knowledge, or the means of knowledge, declared that they were satisfied of their correctness, holding that if a purchaser, choosing to judge for himself, did not avail himself of the knowledge, or means of knowledge, open to him or to his agents, he could not be heard to say he was deceived by the vendor's representations, the doctrine of caveat emptor applying in such case, and the knowledge of his own agents being as binding as his own knowledge.

Slaughter's Administrator v. Gerson/Opinion of the Court