Keplinger v. De Young was a case heard by the United States Supreme Court in 1825 that dealt with the issue of whether or not an individual can be held liable for damages caused to another person's property due to their negligence. The plaintiff, Keplinger, argued that he had been injured when his horse and wagon were damaged after being driven over a bridge owned by defendant De Young which had collapsed due to its poor condition. The court ruled in favor of Keplinger, finding that De Young was indeed negligent and thus responsible for any damage done as a result of his failure to properly maintain the bridge. This ruling established precedent for holding individuals accountable for damages resulting from their own negligence and set forth important principles regarding liability law which are still applicable today.

In Keplinger v. De Young, the Supreme Court was asked to determine whether a contract between two parties that had been partially performed could be enforced by law. The majority opinion held that such contracts were enforceable and should be upheld in court. However, Justice Story dissented from this decision on the grounds that partial performance of a contract did not necessarily indicate an intent to enter into a binding agreement; rather, it might simply reflect an expectation of future payment or other consideration for services rendered thus far. He argued that if courts were to uphold such agreements as legally binding then they would essentially become guarantors of debt and creditors would have no incentive to ensure their own security before entering into contractual arrangements with others. Furthermore, he noted that there was no clear legal precedent for enforcing incomplete contracts and therefore any ruling in favor of doing so would set dangerous new precedents which could lead to unforeseen consequences down the line.