Prime Minister Lee and his father Lee Kuan Yew, have often sued media
A Singapore court has ruled that the Far Eastern Economic Review did defame the country's founder Lee Kuan Yew and his son Prime Minister Lee Hsien Loong.
The Court of Appeal rejected an attempt by the magazine and its editor, Hugo Restall, to have their conviction in September 2008 overturned.
Singaporean leaders have won hundreds of thousands of dollars in damages from critics and foreign publications.
They say the lawsuits are necessary to protect them from unfounded attacks.
Lee Kuan Yew, 86, now a senior cabinet adviser, served as prime minister from 1959 to 1990. Lee Hsien Loong, 57, took over in 2004 from Goh Chok Tong.
The Lees alleged defamation in a 2006 article published in the Far Eastern Economic Review (FEER) based on an interview with Chee Soon Juan, an opposition party leader.
The article - entitled "Singapore's 'Martyr,' Chee Soon Juan" - described the Singapore Democratic Party secretary general's battle against the ruling People's Action Party and its leaders.
Last month Dow Jones announced that it would close FEER, which was founded in 1946.
In a separate court case, a group of pro-democracy activists were acquitted of involvement in an illegal march two years ago.
Public prosecutors had charged the five activists with "participating in a procession without a valid permit".
But District Judge John Ng ruled that there was no evidence to support the government's case, AFP news agency reported.
The activists were charged after walking together wearing T-shirts with the words "Democracy Now" and "Freedom Now" in order to circumvent laws against public assemblies of more than four people.
Chee Siok Chin, one of the five acquitted activists, said the court ruling should not be seen as a step forward for pro-democracy activists in Singapore.
"It still does not vindicate the fact that we were exercising our basic rights, although I do hope this ruling will encourage Singaporeans to see this type of peaceful assembly is no big deal," Ms Chee was reported as saying by AFP.
"It's really nothing sinister, it's not trouble making," she added.
Earlier this year, Singapore tightened its already stringent rules on public assembly ahead of Singapore's hosting of the APEC summit next month which will bring 21 heads of state to the city.