Alito wrote that "the prayers of so many people from around the country were a palpable and powerful force. As long as I serve on the Supreme Court, I will keep in mind the trust that has been placed in me," Dobson said on his radio broadcast.
Supreme Court spokeswoman Kathy Arberg said Alito's note was in response to a letter Dobson sent congratulating him on his confirmation. She said his pledge to "keep in mind the trust that has been placed in me" was included in many replies he wrote to congratulatory letters.
David Yalof, a political science professor at the University of Connecticut and the author of a book on Supreme Court vacancies, said Alito's letter did not appear to violate ethical standards.
"I think it's a very carefully worded letter, and I don't think any of it crosses the line," he said. "As long as Alito didn't (say) there is any obligation or debt owed, I don't think it is a violation of judicial canon."
Americans United for Separation of Church and State called the letter "grossly inappropriate."
"This note strongly suggests that Alito is carrying out a right-wing agenda instead of being a justice for all," said the Rev. Barry W. Lynn, executive director of the group.
In a statement released Wednesday, Dobson responded: "The wild speculations by Barry Lynn and others about Justice Alito's judicial philosophy or intentions are nothing short of ridiculous."
Focus on the Family declined to release a copy of Alito's letter but confirmed the wording read by Dobson.
Dobson had urged his listeners to support the nominations of Alito and Chief Justice John Roberts. On Wednesday, he said that support had "affected history" by helping put both men on the court in time to hear a pending case on an abortion procedure that opponents call "partial-birth abortion."
Focus on the Family, a conservative Christian ministry based in Colorado Springs, says Dobson's show, its other broadcasts and its publications reach more than 200 million people worldwide.