Millionaire Louise Vanderbilt has won what may be her last battle in an ongoing war with her landlord.

On Friday, Superior Court Judge Thomas H. Needham ruled that an eviction order served by Harry B. Casey, Vanderbilt's landlord and Newport's county sheriff, was invalid.

The fight began last July when Casey raised Vanderbilt's monthly rent for two apartments in "Mailands," one of Newport's several Victorian mansions, from $950 to $2,950.

"Justice wins out," was the 63-year-old Vanderbilt's response after the ruling was announced.

Principle and not money has been at the heart of the matter. The widow of George Vanderbilt - who was the grandson of Cornelius, the man who built the railroads - she is heiress to one of America's great fortunes. Nor did she need the order to keep a roof over her head. Last week she moved to another home in Newport, saying that the apartment in "Mailands" was "insufferable in the summer."

Vanderbilt's outrage at the 300 percent increase in her rent and Casey's indication that within the next five years she could have expected to pay more than $4,000, prompted her to join a Newport tenant's association. As a member of the organization, made up mostly of low-income families, Vanderbilt asked the city council to enact a rent control measure.

Having won her personal victory, she is not abandoning her fellow tenants' causes, but intends to remain an active member of the group.

"I don't like to see people kicked around as I have been," she explained.