Minnesota's popular practice of registering voters at the polls on Election Day came under a sharp legal attack in federal court Friday from activists and a state legislator who argued that those ballots are cast and counted before the voters' eligibility can be fully checked.

As a result, said lawyer Erick Kaardal, it is impossible to "claw back" votes if people are determined later to have been disqualified due to felony conviction or a question over residency or citizenship. He asked a federal judge to step in and order major changes to Minnesota's 38-year-old Election Day registration system, which attracted 542,257 voters in 2008 and is a factor in keeping the state at the top of the nation's voter-turnout lists.

"Just don't stuff the ballots into the ballot machine before ineligible voters are excluded," Kaardal told the courtroom.

He spoke at a hearing before U.S. District Court Judge Donovan Frank in a case that has opened a second front in Minnesota's battle over election law. Representing the Minnesota Voters Alliance, the Minnesota Freedom Foundation, Republican Rep. Sondra Erickson of Princeton and others, Kaardal proposed either doing rigorous database searches at the polling place or holding off on counting ballots of same-day registrants until they can be thoroughly vetted.

The case has themes similar to a pending state Supreme Court petition brought by the League of Women Voters, Common Cause and others. The state case seeks to block a proposed photo ID constitutional amendment that will be submitted to voters in November.

In the federal case, lawyers for the state and three counties named as defendants -- Ramsey, Chisago and Crow Wing -- argue that officials are complying with existing state laws, that the system the activists are proposing would assume voters are "guilty" until proven otherwise, and that it would ultimately disenfranchise large numbers of people who register on Election Day.

"That's what the plaintiffs are trying to do," said Robert Roche, representing Ramsey County.

The judge questioned both sides extensively and said he would rule within two months.

The suit is built on a series of widely scattered election problems, including 10 voters in Harris, Minn., in 2006 who gave an address that turned out to be that of a coin laundry; felons who were prosecuted after the fact for voting before their civil rights were restored; and questions about the eligibility of two people with disabilities who voted in 2010 in Crow Wing County. The fact that thousands of postcards sent to Election Day registrants have been returned as undeliverable also was cited as a potential red flag.

Rewriting election code

Kaardal said the unifying problem is the difference in the way registrants are checked.

The names of those who register before the election are run through various government databases to verify their citizenship, age and address, and to ensure they are not ineligible due to a felony conviction or a court order. Those registering at the polling place, Kaardal said, go through no such checks until long after their ballots have been counted.

The judge noted that these registrants sign their names to statements that carry their felony penalties for perjury. He noted that state databases may show the wrong information about an eligible voter because people's information is constantly changing. "I could have moved," the judge told Kaardal.

Roche said Kaardal and his clients were "asking us to rewrite Minnesota's election code.'' He said Minnesota law is built on "liberally interpreting voting rights" and the lawsuit is asking the judge to change that tradition.

After the hearing, Kaardal said he and his clients were not trying to halt same-day registration and did not want to turn every such vote into a "provisional" ballot that can't be counted until the voter is checked out. He said the best solution would be for the state to perform database checks at the polling place.

Secretary of State Mark Ritchie, a defendant in both suits, has said it would be impossible to duplicate those extensive checks at the polling place, and such a requirement would threaten Election Day registration.

Mike Dean, executive director of Common Cause, which is a plaintiff in the state suit, said in a statement Friday that the federal lawsuit and the photo ID amendment are part of a strategy to end same-day registration.

Jim Ragsdale • 651-925-5042