Nessel sought to shut down Line Five shortly after taking office in 2019, arguing the oil-transporting pipeline was operating in violation of the state Environmental Protection Act.
Last year, the Michigan Public Service Commission approved the construction of a tunnel around Line 5 in what regulators said was a decision that would allow the line to operate with less fear of a spill.
The case today was only directly about whether the issue should be heard in state or federal court.
