In both cases, the couples had prepared for a medical emergency, creating living wills, advanced directives and power-of-attorney documents.

As recounted by Ms. Langbehn, the details of the Miami episode are harrowing. It began in February 2007, when the family  including three children, then ages 9, 11 and 13  traveled there for a cruise. After boarding the ship, Ms. Pond collapsed while taking pictures of the children playing basketball.

The children managed to help her back to the family’s room. Fortunately, the ship was still docked, and an ambulance took Ms. Pond to the Ryder Trauma Center at Jackson Memorial. Ms. Langbehn and the children followed in a taxi, arriving around 3:30 p.m.

Ms. Langbehn says that a hospital social worker informed her that she was in an “antigay city and state” and that she would need a health care proxy to get information. (The worker denies having made the statement, Mr. Alonso said.) As the social worker turned to leave, Ms. Langbehn stopped him. “I said: ‘Wait a minute. I have those health care proxies,’ ” she said. She called a friend to fax the papers.

The medical chart shows that the documents arrived around 4:15 p.m., but nobody immediately spoke to Ms. Langbehn about Ms. Pond’s condition. During her eight-hour stay in the trauma unit waiting room, Ms. Langbehn says, she had two brief encounters with doctors. Around 5:20 a doctor sought her consent for a “brain monitor” but offered no update about the patient’s condition. Around 6:20, two doctors told her there was no hope for a recovery.

Despite repeated requests to see her partner, Ms. Langbehn says she was given just one five-minute visit, when a priest administered last rites. She says she continued to plead with a hospital worker that the children be allowed to see their mother, even showing the children’s birth certificates.

“I said to the receptionist, ‘Look, they’re her kids,’ ” Ms. Langbehn said. (Mr. Alonso, the hospital spokesman, says that except in special circumstances, children under 14 are not allowed to visit in the trauma unit.)