Merle received her Bachelor of Arts in government and Spanish, with honors, from the University of Texas at Austin in 2005 and she graduated, cum laude, with a Juris Doctor from the New York University School of Law in 2008.

From 2013 to 2015, Merle was a litigation associate and civil rights fellow at Fried, Frank, Harris, Shriver & Jacobson in New York City.

President Biden nominated Merle to a new seat created following the appointment of Roslynn R. Mauskopf as director of the Administrative Office of the United States Courts.

[14] During Merle's confirmation hearing, Republican senators criticized her over comments she made in 2017 in which she said that proposals for voter ID laws and a border wall were based in white supremacy.

[18] On January 3, 2023, her nomination was returned to the President under Rule XXXI, Paragraph 6 of the United States Senate; she was renominated later the same day.

[16] Merle was President Biden's 100th district court judge to be confirmed.