BEIJING -- U.S. and Chinese trade negotiators ended months of hard bargaining nearly 4 1/2 years ago with a breakthrough agreement to stop China's runaway piracy of movies and software. Fifteen months later, the negotiators had to redraft the accord to close loopholes China exploited.

With its landmark deal this week to open markets to U.S. business and the promise of entry to the World Trade Organization to follow, Beijing faces new globally enforced rules. And the question for China's trading partners is: Will the future be any different?"This country has been ruled by consensus for thousands of years. You cannot change it overnight," said Shawn Xu, an economist with the investment house China International Capital Corp. "The international community is going to have to give China some time."

If past is prologue, China's membership in the global trading club could be tarred by broken or hedged promises. Take the international treaty banning trade in endangered animals, which is spottily enforced, or the 1995 intellectual property protections with the United States, which had to be renegotiated in 1996.

But there are encouraging signs. China's communist leaders have expended much political capital to overcome domestic opposition to joining the capitalist WTO.

They see WTO with its free markets and fair-play rules as a way to prod long-protected state industries to reform or face unforgiving foreign competition. It would also help build a more western-style legal system better suited to running the dynamic economy than the current mix of central fiat and imperial bureaucracy.

Since Monday's market-opening deal with the United States, Chinese leaders have devoted the entirely state-controlled media to selling WTO to a nationalistic public and skeptical business interests.

"Under the agreement, China will have to do things according to international rules," People's Daily today quoted China's chief WTO negotiator, Long Yongtu, as saying. "This cannot be called a concession. Following the rules is the duty of every responsible nation."

The same protections that WTO membership affords other countries will also protect Chinese exports, ventures and markets abroad, Long argued.

Although U.S. trade negotiators called the agreement "comprehensive," China still can slow inroads by foreign companies. Financial and telecommunications firms given greater leeway under the accord will still need government-issued licenses. Capital controls and the inconvertibility of the yuan will dampen foreign bankers' interests.

"In the end of the day, they have a million ways to write rules to frustrate an agreement," said Gordon Chang, a Beijing-based lawyer with Paul, Weiss, Rifkind, Wharton and Garrison. "China will find itself in perpetual litigation in WTO dispute panels."

Pressures to delay living up to WTO terms will grow if recalcitrant state factories go under in dizzying numbers and unemployment soars, Chang said.

But China, as negotiator Long noted, is in need of foreign capital and has to play by the rules to attract it. Investors' fervor for China cooled further after the trading arm of a wealthy provincial government collapsed. Foreign lenders to GITIC are still trying to recover $3 billion in debt.

"The Chinese learned a hard lesson: If you don't comply with international practices and international laws, you will get punished," said China International Capital's Xu. "There'll be no more lending from foreign banks."

Even if China ends up with a mixed record in WTO, the People's Republic would hardly be alone. Japan joined the world trade system 45 years ago and still has disputes with the United States and other trading partners.

"There are going to be plenty of problems, and we can expect unevenness in the PRC's compliance, just as there is an unevenness in their ability to comply with their own rules," said Dean Ho, chairman of the American Chamber of Commerce in Shanghai and vice president of Unison, an investment fund.

"There will be disappointments in the implementation. But overall, this is a step in the right direction. It's better than no agreement."