Chinese legislators just updated the country’s advertising law, which hadn’t been overhauled since 1994 — well before the arrival of many Western brands, and before the internet took off.

The legislation, which goes into effect Sept. 1, 2015 will affect everything from brands’ use of celebrity endorsers to how baby formula can be promoted. It bans the use of China’s flag in ads. It says people must be able to close online pop-up ads with a single click (intrusive ads are still ubiquitous on China’s internet). And in a country of more than 300 million smokers, the law cracks down harder on tobacco advertising.

The updated legislation fits into a general trend of strengthening consumer protections in China, where food-safety scandals and quality issues are common, and it increases fines for false advertising.

Many advertising regulations have not been strictly enforced in the past, and there are questions about what will happen this time. But regulators recently fined P&G’s Crest brand a record $963,000 for false advertising because it used computer software to whiten a celebrity endorser’s teeth.

That suggests “enforcement authorities are not afraid of using this kind of fine, especially once the new law has come into effect,” said Eugene Low, partner at the Hong Kong office of Hogan Lovells law firm. “And apart from financial implications, it can also cause reputation implications for companies, because their name gets put on a web site, sending a message to the public that the Chinese government doesn’t tolerate this kind of advertisement.”

Read more details on the changes from AdAge here.