A decision on Tuesday by the European Union’s highest court, striking down an agreement between the E.U. and the United States that allows companies like Facebook and Google to store the personal data of European users on servers in America, was considered a victory by some privacy advocates. But in practice the ruling will do little to protect privacy unless lawmakers in Europe and the United States pass stricter privacy laws.

The agreement was meant to make it easy for technology companies to operate in Europe and the United States without worrying about setting up separate servers in each place. Under the pact, E.U. officials treated American laws as sufficient to protect the privacy of Europeans. But the European Court of Justice said that American laws do not adequately protect emails, social media information and other personal data stored on servers in the United States from surveillance by the National Security Agency and other United States government agencies. It also directed European regulators to investigate complaints from Europeans that their data is not secure when it is transferred abroad.

The ruling might make it harder for a few American businesses to operate in Europe, because they could be forced to separate personal data according to where users live. But legal experts and Internet executives say that most large technology companies can continue to store data about Europeans on servers in the United States under other rules that were not struck down by the court. Companies can also move data if their customers have allowed them to do so by agreeing to a standardized contract. European and American officials have also said that they are negotiating a new data-storage agreement, which could be completed in the next few months.

The real problem is that privacy laws and rules in the United States and Europe are far too lax, and there are few indications that officials are willing to strengthen them. This summer, Congress adopted reforms to impose some limits on the N.S.A.’s bulk data collection, but those changes contain a number of big loopholes. And a 2012 proposal by President Obama for a “privacy bill of rights,” which would have given consumers more control over how businesses collect and use their information, has not moved in Congress.