Aetna Life Insurance Company v. Middleport is a United States Supreme Court case that was decided in 1887. The case involved a dispute between Aetna Life Insurance Company and the town of Middleport, Ohio. Aetna had issued a policy of life insurance to a resident of Middleport, and the town had imposed a tax on the policy. Aetna argued that the tax was unconstitutional, as it violated the Contract Clause of the United States Constitution. The Supreme Court agreed with Aetna, ruling that the tax was unconstitutional. The Court held that the Contract Clause prohibited the state from passing laws that impaired the obligation of contracts. The Court reasoned that the tax imposed by Middleport was a form of impairment, as it changed the terms of the contract between Aetna and the insured. The Court also held that the tax was not a valid exercise of the state's taxing power, as it was not a tax on the property of the insured, but rather a tax on the contract itself. In conclusion, the Supreme Court held that the tax imposed by Middleport was unconstitutional, as it violated the Contract Clause of the United States Constitution. The Court's decision established that states cannot pass laws that impair the obligation of contracts.

In Aetna Life Insurance Company v. Middleport, the Supreme Court was asked to decide whether a contract between an insurance company and its insured could be enforced when it had been made without consideration. The majority of the court held that such contracts were unenforceable because they lacked consideration, but Justice Field dissented from this opinion. He argued that if parties entered into a contract in good faith and with no intention of taking advantage of each other, then there should be no need for consideration to make it enforceable. Furthermore, he noted that while some states may require consideration as part of their laws governing contracts between insurers and insureds, nothing in federal law required it; thus any state-level requirement should not apply here either. In conclusion, Justice Field believed that since both parties had acted in good faith at the time they entered into their agreement - even though there was technically no "consideration" exchanged - then the contract should still be enforceable by law regardless of what state statutes might say otherwise.