Taking away a naturalized American's citizenship means proving lies in federal court

Officials cannot cancel an American's citizenship the way they cancel a visa. The government must sue in federal court and convince a judge that the person won citizenship through a lie that mattered to the decision to grant it.

That test is at the center of the investigation into Ilhan Omar, the Democratic representative from Minnesota in Congress. Federal agents searched her Washington home and took her phone, notebooks, computers, and passport as part of an effort to build a case that might end with her losing citizenship and facing deportation.

To bring that kind of case, investigators must look backward at how citizenship was obtained. Officials are reviewing documents tied to her family's arrival, including steps taken by her late dad, who led her and additional relatives to the U.S. in 1995 out of a Kenyan refugee camp.

Omar says she did not commit immigration fraud, and her office said the president wants to silence a progressive voice in Congress. The Trump administration's effort to take citizenship away from naturalized Americans over alleged lies in their applications is unprecedented, but winning is difficult. Most of the Justice Department cases started this term are still undecided. The outcome remains unclear.