It's the state's turn to make its case that Pennsylvania's voter identification law conforms to the state constitution.
Lawyers in the 8-day-old Commonwealth Court trial are to begin presenting witnesses Wednesday.
Plaintiffs want to overturn a March 2012 law requiring all voters to show an acceptable photo ID as a condition of casting a ballot.
Plaintiffs including the NAACP, the League of Women Voters and Philadelphia's Homeless Advocacy Project say the law cannot be implemented without disenfranchising large numbers of voters.
The law has yet to be enforced by court order, pending the constitutional challenge.
Lawyers for the state say it's done everything possible to make IDs widely available, including the creation of a Department of State ID that registered voters without other ID can get for free.