Advocates say the law empowers and informs family caregivers, fills a gap in the current health care system between the hospital and patients' families.
They say caregivers are now part of the patient care team and entitled to vital health information.
"Unless you've had the experience, you really have no idea that there's a big puka in the system," said Pat Bemis, a former nurse and caregiver for her husband, who's batting Parkinson's Disease.
Because of his condition, he didn't understand the instructions when he was discharged from the hospital.
"He said 'I have a return appointment' and that wasn't the whole story. There were a lot of other things that needed to go on and a lot of precautions that I wasn't aware of," she said.
Under the new law, Bemis would have been the designated caregiver and more informed upon admission and discharge.
There are three parts to the new law.
Identification - The patient has the opportunity to designate a family caregiver when they are admitted to the hospital.
Notification - The family caregiver must be notified if their loved one is discharged from the hospital or transferred to another facility.
Instruction - Hospitals must offer family caregivers instruction on medical tasks they will need to perform at home.
The law also entitles people to vital information on how to care for their family member in the hospital and how to take care of them once they are discharged," said Barbara Kim Stanton, AARP state director.
The law impacts 154,000 family caregivers in the islands. Some hospitals already designate a family caregiver, but the new law ensures that happens.
AARP has an 'I Heart Caregivers' campaign where caregivers can get free information cards on their rights and gift cards for gas, groceries or the drug store when they share their family stories.