The Obama administration issued a final rule Friday requiring insurers to treat mental health and substance-abuse problems the same way they do physical illnesses.

The rule provides long-awaited clarification on a mental-health parity law that was enacted with much fanfare five years ago but had not been fully implemented as the federal government wrote and revised the regulations.

It also represents a fulfilment of a promise made by President Barack Obama, who vowed to put the finishing touches on the regulations as part of a broader effort to address the problem of mass shootings, which have thrust mental health issues into the spotlight in recent years.