When Lili J. Silvera said she wanted to move back to California to help care for her elderly mother, her husband, Cabot Professor of the Natural Sciences Isaac F. Silvera, agreed that after 36 years of marriage, it was time for him to follow her for a change.

When they tried to move back into an apartment in the home she and her sister have owned for decades in North Beach, Calif., they faced one major problem-the elderly tenant who rented one of the apartments from them for 31 years refused to leave.

The tenant, Alvin Leong, who is 74, claimed that it was illegal for the Silveras to evict him.

According to San Francisco rent laws, owners are allowed to evict their tenants and move into the vacant apartments as long as the owners plan to live there permanently for at least a year.

However, because Silvera is teaching a seminar at Harvard this fall, Leong and his family claimed that the Silveras did not intend to live in the apartments for a full year and the because of this, the eviction was invalid.

The Silveras served Leong with an eviction notice on Jan. 14, giving him 30 days to move out.

Leong's family, assisted by their lawyer, Gen Fujioka, a staff attorney for the Asian Law Cancus, filed suit in civil court to challenge the eviction.

"[Alvin] is really helpless. Since his income is limited, he doesn't really have too many options," said Leong's daughter.

The result was a hung jury, and the judge advised Leong to settle his claim.

The Silveras reluctantly agreed to pay Leong $5,000 and to give him free rent until November, when he is scheduled to leave the apartment.

"We didn't want to settle because we had a legal right to be there," Mrs. Silvera said.

The Silveras said the eviction is ethical.

"The law is quite clear in what it states in that as owner, we can occupy our property," Professor Silvera said.

The Silveras decided to move into the two apartments for several reasons, the professor's wife said.

Professor Silvera, who recently received an appointment to the University of California, is co-writing a book about Albert Einstein with UC Professor Dan Rocher, and plans to spend a large amount of time there, she said.