True. It is Massachusetts v. United States Department of Health and Human Services that was decided on the basis that the law was a violation of the 10th Amendment and the Spending Clause. Note that this was a suit brought by a state. Other suits were brought by individuals and the states’ rights question was not an issue. The trial judge ruled that the law was unconstitutional:
On July 8, 2010, exactly one year after the suit was filed, Judge Tauro released his decision in the case. He ruled that DOMA section 3 violates the Tenth Amendment and falls outside Congress’ authority under the Spending Clause of the Constitution.
The appeals court also found the law unconstitutional but rejected the argument concerning the 10th Amendment and the Spending Clause. However, the court stayed its ruling pending review by the Supreme Court. The Supreme Court, however, did not hear Massachusetts but took up Windsor instead. After the decision in Windsor, the other cases, including Massachusetts, were dismissed as moot so the 10th Amendment question remains unresolved.