While prosecutors argued Monday for a broad expansion of the state’s ability to subpoena citizens in criminal investigations, the public defenders office claimed the change would effectively eliminate the Fourth Amendment to the U.S. Constitution.

Connecticut’s criminal justice system differs from that of many other states in that it is difficult for police or prosecutors to compel anyone to give testimony in criminal cases. Currently, in order to convene a grand jury capable of issuing subpoenas, the state must demonstrate before a panel of judges that it has exhausted all other means of investigating a crime.

The legislature’s Judiciary Committee heard testimony Monday on a bill that would significantly ease the burden prosecutors must meet before seeking a grand jury. Rather than needing to exhaust all their options, under the bill prosecutors would only need to demonstrate that a grand jury investigation would “serve the interests of justice.”

The bill would also leave discretion as to whether to empanel the grand jury up to one judge, rather than a panel of three.

The legislation pits the state’s top prosecutor against its senior public defender, who seemed to agree only on the idea that the bill represents a “radical” change to the state’s current system.

Chief State’s Attorney Kevin Kane has argued for years that prosecutors should have broader subpoena powers in criminal investigations. He said the current process in Connecticut is so stringent that prosecutors rarely apply for a grand jury.

“It can take us six weeks to two months to do the investigation necessary just to apply for the grand jury. We know what a lengthy process that’s going to be, we know how difficult the standard is, so we very rarely apply,” he said.

Kane said the belief that offenders will be caught should be the biggest deterrent to crime. But he said the state has neglected to ensure that law enforcement officers and prosecutors have the ability to solve crimes as they occur.

He recalled trying to investigate a homicide that occurred in a bar where a body was found sitting on a stool. Although Kane said there were people in the bar, when asked by investigators, every potential witness reported being in the restroom when the crime occurred.

“We have no authority whatsoever other than asking a person ‘Would you like to come into the office so we can ask you questions? Can we talk to you?’ If they say ‘No,’ there’s absolutely nothing we can do,” he said. “We could have an eye witness to a crime on camera standing there watching it happen. We can go and ask that person what he or she saw but they don’t have to tell us a word.”

However, Chief Public Defender Susan Storey said the changes Kane seeks would circumvent both the state and federal constitution. She said it would bypass the Fourth Amendment to the U.S. Constitution, which protects citizens from unreasonable searches and seizures.

While statute currently requires investigators to show probable cause to believe that a grand jury will find that a crime has been committed, Storey said that the bill deletes all references to probable cause in favor of requiring that the “interests of justice” be served by the empaneling of a grand jury.

“I think we all know what probable cause is. And judges know how to determine probable cause. For the life of me, I do not know what ‘the interests of justice’ means . . . If somebody can define it for me, I’d appreciate it,” she said.

Storey said the bill seemed to be intended to bypass current investigative procedures in the interest of convenience. She said the legislation would enable any prosecutor to call for a grand jury and compel witnesses to testify whenever they suspect a crime has been committed.

“This is obviously a tool to compel people to talk. And I think it has stripped away all the safeguards that our present grand jury system has,” she said.

Moira Buckley, president of the Connecticut Criminal Defense Lawyers Association, said the legislation consolidates investigation powers within the state’s attorney’s office.

“The current proposal guts the entire investigatory grand jury process and procedure as it exists in Connecticut and replaces it with a process that is controlled by the state’s attorney’s office,” she said.

Kane and Deputy Chief State’s Attorney Leonard Boyle said they did not believe the bill violated the constitution, given that other states and the federal government have more lenient grand jury requirements.

Boyle said the legislation would reduce opportunities for prosecutors to “go on a witch hunt” because a judge would need to authorize any subpoena before it is issued.

“Is it possible for a prosecutor to go on a witch hunt? Sure, there is. We have to admit that. But there are a thousand unsolved homicides in the state of Connecticut,” he said. “. . . That we would sacrifice the effective ability to solve violent crimes because of the risk that some prosecutor might go overboard seems to me to stand public policy on its head.”