Story highlights Letter to Pennsylvania officials explains Justice Department's investigation

Letter calls for Pennsylvania to submit wide range of documents to Justice Department

Justice Department already filed suit against two other states: South Carolina and Texas

The Justice Department Monday launched a formal investigation into whether Pennsylvania's voter law requiring a photo ID discriminates against minorities, and demanded state elections officials produce detailed documents within 30 days.

In a three-page letter to the top Pennsylvania elections official Carol Aichele, Assistant Attorney General Thomas Perez said the Justice Department is reviewing the law "which establishes among other requirements that voters provide photographic proof of their identity as a prerequisite to vote."

Pennsylvania is the first state outside of the areas covered by Section 5 of the Civil Rights Act designed to protect minorities in states with historic racial discrimination in voting, to be investigated. To date the Justice Department has already filed suit against two states: South Carolina and Texas. Officials are awaiting a ruling by a panel of federal judges in Washington, D.C., on a Texas case argued in early July. Judges have scheduled a hearing on the South Carolina case later this summer.

The Pennsylvania letter called for a wide range of documents and data to be submitted to the Justice Department within 30 days. The Civil Rights Division has taken an aggressive approach to challenging voter photo-ID laws, which many Democratic and minority groups claim is an effort by Republican-controlled state governments to suppress voter turnout. Republicans have charged the challenges reflect purely partisan politics designed to enhance minority turnout at the polls.