While pirate radio broadcasters have been around for decades, the FCC recently has begun to crack down on them, conducting more than 300 investigations in the last three years.

In December, the FCC proposed a fine of $453,000 against a Boston operator for apparent unlicensed and unlawful broadcasting, the largest fine ever against a pirate operation.

Since then, a tougher pirate-radio law enacted in January gives the FCC authority to levy higher fines than before — up to $100,000 per violation, which could be for every day of illegal broadcasting, and $2 million in total.

The fines can be levied against station owners and "any person who facilitates pirate radio broadcasting ..."

Also, the FCC can refer cases to a U.S. attorney’s office, which can obtain warrants to have the U.S. Marshals Service seize radio equipment. This has been used in four cases — two in Boston and one each in New York and Miami.