But the Bush administration said the case falls squarely within terms set by Congress to exempt government agencies from lawsuits.
Barbara Dolan, who is suing the United States Postal Service, suffered wrist and back injuries when she fell in 2001 in front of her Glenside, Pa., home in suburban Philadelphia. The mail was placed on her porch instead of in her mailbox.
The case involves a federal law that bars claims arising out of the "loss, miscarriage or negligent transmission of letters or postal matter." Congress passed the law with the intention of keeping excessive lawsuits from disrupting mail flow.
Responding to a question from Chief Justice John Roberts, Dolan's attorney, James Radmore, said "negligent transmission" applies to damage to mail, not to personal injuries.
Patricia Millett, representing the Bush administration, said the Postal Service delivers about 660 million pieces of mail each day and is defenseless when it gets these types of complaints because they are difficult to investigate and defend.
Justice Ruth Bader Ginsburg asked Radmore how the post office would be able respond to complaints long after the incident in question if there are few witnesses.
Radmore said that just as private delivery services are able to handle lawsuits, the government could too. He said the government was exaggerating the risk of frivolous suits.
Dolan lost in the lower courts, but her attorney noted that different federal circuits have defined mail delivery differently.
Federal courts in eastern Pennsylvania, where Dolan lives, decided on an expansive definition of negligent transmission, saying that it ended when the postal service deposited the material on Dolan's porch, thus barring her claim.
Federal courts in New York have said that negligent transmission is limited to the loss or miscarriage of postal material, a more narrowly defined exception which would seem to allow claims like Dolan's.
Monday's hearing took a light note at times. Justice Stephen Breyer brought up a hypothetical situation of whether he could sue for public humiliation if he purchased a toupee by mail and the package fell open.
Roberts joked to Radmore that he could be responsible for a future change in postal policy that made all customers come to the Post Office to pick up their packages.
The case is Dolan v. United States Postal Service, 04-848.
By Kimberly Hefling