Last November on Election Day, thousands of Maryland residents received automated phone calls assuring them that Democratic Gov. Martin O'Malley had already won his race for reelection against former Republican Gov. Robert L. Ehrlich Jr. The calls urged listeners to "relax" and stay home to watch the outcome on TV rather than go out and vote — even though the polls were still open.

The calls, directed at predominantly African-American communities, sounded like a clear attempt to suppress the vote for Governor O'Malley, to Mr. Ehrlich's benefit. It was a dirty trick, and yesterday, a Baltimore City grand jury concluded that it may also have been against the law. The grand jury handed down indictments against two political operatives associated with Mr. Ehrlich's campaign on charges of election fraud and conspiracy to suppress voter turnout in the communities targeted by the calls.

The grand jury charged Julius Henson and Paul Schurick each with three counts of conspiracy to violate state election laws, one count of attempting to influence a voter's decision and one count of failing to provide an authority line on campaign material. Mr. Schurick also was charged with one count of obstruction of justice.

The indictment of Mr. Henson is not likely to send shockwaves through the Maryland political establishment. A longtime Baltimore operative who normally works for Democratic candidates but who was paid $111,000 to switch sides in the 2010 gubernatorial race, he is known for his bare-knuckled approach to political advocacy. In 1998 his handiwork included an effort to smear GOP gubernatorial candidate Ellen R. Sauerbrey as a racist. The following year he disrupted a key endorsement for Mr. O'Malley when the then-Baltimore City councilman was running for mayor. He was fired in 2002 from Lt. Gov. Kathleen Kennedy Townsend's campaign after he called Mr. Ehrlich a Nazi.

Mr. Schurick is a different story. He was a key aide to William Donald Schaefer in both City Hall and the State House. He later served as Mr. Ehrlich's communications director when he was governor and was one of the candidate's top campaign aides last year. Although his years with the Republican Mr. Ehrlich left him estranged from the Democrat-dominated power structure in Maryland, he remains a substantial figure in the state's recent political history.

The Maryland General Assembly passed a law in 2005 making it illegal for any person to "willfully and knowingly influence or attempt to influence a voter's decision whether to go to the polls to cast a vote through the use of force, fraud, threat, menace, intimidation, bribery, reward, or offer of reward." The law imposes criminal penalties of up to five years in jail if prosecutors can prove a defendant knew about the law.

Yet after questions were raised about the origins of the 2010 incident, Mr. Henson seemed happy to take credit for the calls, telling reporters that they were intended to rally Republican voters rather than to keep Democrats away from polls. Under the circumstances, that explanation seemed utterly nonsensical, but for prosecutors the most pertinent aspect of his comments may have been his insistence that he took care to avoid violating the 2005 law. That could make it hard for him to convince a jury he didn't know about it. Likewise, Mr. Schurick would be hard pressed to plead ignorance, since he was working at Governor Ehrlich's right hand when the law was passed.

Mr. Ehrlich has not been charged with any wrong-doing, though he and some of his aides reportedly were called to testify before the grand jury. He has denied knowing anything about the 112,000 robo-calls made by Mr. Henson's firm, Universal Elections, even though his campaign paid the company to conduct "community outreach."

Mr. Henson and Universal Elections are also facing a multimillion-dollar civil suit from Maryland Attorney General Douglas F. Gansler and the U.S. Department of Justice's Civil Rights Division for their alleged efforts at voter intimidation and suppression.

Mr. Henson has long boasted there will always be a demand for the kind of political tactics he engages in because they are effective. But this time, regardless of the outcome of the criminal case, he has likely gone too far. A political operative whose stock in trade is helping candidates secure votes in the African-American community is unlikely to be effective after he's admitted to a scheme clearly designed to suppress black votes.

But if this case is going to have a lasting effect on the way politics are practiced in Maryland, it will be the result of the indictment of Mr. Schurick. Mr. Henson's criminal problems can be dismissed as a dirty tricks operative finally called to account, but Mr. Schurick is a mainstream figure. Ehrlich campaigns have traditionally been bruising affairs — witness the busing of homeless men from Philadelphia to pass out misleading campaign literature in 2006 — but the reach of this investigation to someone so close to the top is nonetheless surprising. His indictment, let alone a conviction, should make others think twice about crossing the line.