A New York judge has ordered former president Donald Trump's onetime lawyer Rudy Giuliani to testify in the Fulton County district attorney's investigation into efforts to overturn the 2020 election.

Why it matters: Giuliani, who was subpoenaed by the Atlanta DA in early July, is the closest figure to former president to be implicated in the wide-reaching investigation.

Driving the news: A filing Wednesday revealed that a New York state supreme court judge has ordered Giuliani to testify on August 9 before the DA's special purpose grand jury focused on the investigation.

• This comes after Giuliani did not show up for a New York hearing on the matter earlier this month.

What's next: Giuliani could still opt to fight his subpoena in Georgia, as Sen. Lindsey Graham (R-S.C.) and Rep. Jody Hice (R-Ga.) are currently doing.

Threat level: If Giuliani doesn't appear again, he could be subject to a material witness arrest warrant, to compel him to appear.