But the law remains under scrutiny in a federal lawsuit as well.
The Indiana law applies to commercial and non-commercial speech and prohibits automated, pre-recorded calls unless a live operator introduces the message. Schools are exempted, as are organizations that receive a consumer's permission to call.
The General Assembly passed the law 23 years ago but it's only been enforced against political calls for the past six, prompting a wave of state and federal lawsuits. The Indiana Supreme Court's decision Thursday essentially puts an end to the state questions.
"This ruling is a big win for Indiana consumers and the state's strict telephone privacy statute," said Indiana Attorney General Greg Zoeller.
"Over the years we have worked diligently to ensure Hoosiers are not contacted at home with annoying, unsolicited automated calls. Indiana's auto-dialer law exists to prevent everyday citizens from receiving unwanted messages and we will continue to protect this law against any and all challenges."
The state suit was brought by FreeEats.com, which had made robo-calls during a 2006 Congressional campaign. The company argued that the requirement that a live operator introduce the recorded message was a violation of constitutionally protected speech.
But the Indiana Supreme Court said in a 4-1 decision the requirement "does not impose a substantial obstacle on FreeEats's right to engage in political speech," even if it increases the cost of making the calls.
"A conclusion that a statute violates the state constitution when it increases the economic costs to engage in political expression, without any showing that the right to political expression no longer serves its purpose, would be unsound," the court said.
The law remains under fire in federal court. In October, a federal judge ruled that the Indiana law violates the federal Telephone Consumer Protection Act, which regulates calls made from one state to another.
The ruling said that federal law would allow Indiana to prohibit the calls completely. But the state law doesn't do that. Instead, the court said, it regulates the calls by putting restrictions on their use – primarily the requirement that a live operator introduce the call.
Zoeller has appealed the ruling and the U.S. Court of Appeals for the Seventh Circuit has put the order on hold while it considers the case. That stay – combined with the Indiana Supreme Court's decision Thursday – means the law can be enforced.
Over the past two years, more than 10,000 complaints have been filed with the attorney general's office about unwanted telemarketing calls. About 72 percent of the complaints are about auto-dialed calls.
Violations of the law can result in fines of up to $5,000 per call.
Lesley Weidenbener is an editor at TheStatehouseFile.com, an Indiana news website powered by students from the Franklin College Pulliam School of Journalism.