The Justice Department gave California high schools one week to confirm that they will comply with the Trump administration’s stance on transgender athletes as the government takes aim at the state’s regulations allowing students to compete on the basis of gender identity.

Days after a 16-year-old transgender athlete placed first in two events at the California state track-and-field championship, the Trump administration is threatening legal action and “large scale” fines.

AB Hernandez, a transgender athlete, has stirred controversy and drawn national attention over competing in a girls track and field championship. NBC News' David Noriega explains how Hernandez was able to compete under a new California policy.