The death sentence has left many questions unanswered, legal experts said.
Not only was it uncertain whether Li had received a fair trial, but there was the danger that the mainland could continue prosecuting Hong Kong crimes, they said.
'The most significant point revealed by this case is that we don't know what 'one country, two systems' means,' said Fu Hualing, a University of Hong Kong academic specialising in mainland law.
He said it was unclear if Hong Kong was considered part of China under mainland criminal law.
'China has never sent any of its nationals to any other country to face criminal trial. In this sense, it was just following tradition with the Li Yuhui case,' Mr Fu said.
'But if Hong Kong is considered a part of the PRC, then it is supposed to send Li back here.' Mainland authorities claimed they had the right to prosecute Li because, under Chinese law, they can prosecute its nationals even for crimes committed outside the country.