Newdow is most famous for a lawsuit filed on behalf of his daughter against inclusion of the words "under God" in public schools' recitals of the United States Pledge of Allegiance. The 9th U.S. Circuit Court of Appeals found that the phrase constitutes an endorsement of religion, and therefore violates the Establishment Clause of the First Amendment to the United States Constitution. However, the decision was later overruled by the U.S. Supreme Court on procedural grounds, citing that Newdow did not have custody of his daughter and therefore did not have the right to bring suit on her behalf. Newdow has once again filed suit regarding the same issue, but this time on behalf of three unnamed parents and their children. Citing the precedent set by the 9th U.S. Circuit Court of Appeals in the course of Newdow's previous suit, U.S. District Judge Lawrence Karlton has concurred that the pledge is unconstitutional when recited in public schools.

In November of 2005, Newdow announced he wants to have "In God We Trust" removed from U.S. money. In a November 14, 2005 interview with Fox News' Neil Cavuto, Newdow compared "In God We Trust" being on U.S. Currency with segregation (specifically separate drinking fountains), saying "How can you not compare those? What is the difference there? Both of them (whites and blacks) got equal water. They both had access. It was government saying that it's OK to separate out these two people on the basis of race. Here we're saying it's OK to separate two people on the basis of their religious beliefs."

Quotations

"There's a principle here, and I'm hoping the court will uphold this principle so that we can finally go back and have every American want to stand up, face the flag, place their hand over their heart and pledge to one nation, indivisible, not divided by religion, with liberty and justice for all. "

"The government must pursue a course of complete neutrality toward religion. "

"I have the right to bring up my daughter without God being imposed into her life by her schoolteachers."

"One day I was just looking at the coins [-- that] is what brought this up. I saw "In God We Trust" on my coins. I said, "I don't trust in God," what is this? And I recalled there was something in the Constitution that said you're not allowed to do that and so I did some research. And as soon as I did the research, I realized the law seemed to be on my side and I filed the suit. It's a cool thing to do. Everyone should try it."

"This issue is whether or not our government should be infusing religion into [the public schools]. Our churches are very strong in this nation and I think that's great and everybody should have the ability to worship as he or she sees fit. I choose to worship not believing in God and government should not thrust a religious idea down my throat."

"I believe in the Constitution. The Constitution says that government isn't supposed to be infusing religion into our society, and so I asked to have that upheld."

"I think the Constitution has been upheld. I think they made the right decision."

"[America] is the greatest nation and what has made it great is our Constitution. The framers were quite wise in recognizing what religion can do and how it can cause hatred and how it can cause death. You don't have to go far in this world, outside of our nation, to see where that has happened. It is prevalent over the entire globe and the reason we don't have it here is because we have an establishment clause ... If Mike [an audience member and critic] wouldn't mind saying "we are one nation under Buddha" every day, or "one nation under David Koresh" or "one nation" under some religious icon that he doesn't believe in ... if he doesn't understand the difference then we have a problem."

"I feel like I am not an American in the eyes of my government because of their religious beliefs. I think that is un-American."

"Most people I know I think agree and even many theists agree with this. We don't want government involved. When atheists become the majority in this country, I don't think the theists are going to be glad to have "one nation under no God" inserted in the Pledge of Allegiance."

"[Supreme Court Justice Anton Scalia] should be commended for acknowledging that his views are so strong that -- should the Pledge case reach the Supreme Court -- he wouldn't be able to maintain the requisite impartiality."