Michael Newdow, an activist who filed the case on behalf of a group of atheists, said that inscribing the nation's motto on money was a violation of the First Amendment's Establishment Clause, which prohibits Congress from establishing a national religion.
He argued that the federal government has turned atheists into "political outsiders on the basis of their fundamental religious tenant".
The phrase "In God We Trust" first appeared on US coins in 1864, and Congress passed legislation in 1955 requiring all currency to bear the words.
This isn't the first time Newdow has challenged what he deems as the government's endorsement of religion.
In 2004, his case brought to the Supreme Court that the words "under God" in the Pledge of Allegiance violated the First Amendment, was dismissed.
He also attempted but failed to block Chief Justice John Roberts from saying the phrase "So help me God" while administering the presidential oath of office to President Barack Obama during his inauguration in 2009.
Newdow repeated this attempt unsuccessfully for the 2013 and 2017 inaugurations.
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