With his decision, de Sousa returned the text to the Assembly of the Republic (parliament) to modify articles according to which checking of private email is allowed without order from a judge.
The Constitutional Court (TC) unanimously rejected several articles of the legislation on Monday after the president ordered on August 4 to oversee the rule.
In his request, De Sousa said that legislators altered rules not directly specified in the European directive on the matter.
If maintained as it is, it would result in a restriction of the fundamental rights to the inviolability of mail and communications, and to the protection of personal data in the use of computers, president of the TC, Joao Caupers, said in a statement.
At the same time, counselor Mariana Canotilho indicated that there would be a violation of principles reserved to the judge and of the constitutional guarantees of defense in the criminal area.
The legislation proposed by the Government, which facilitates access to the Public Ministry of private communications, was approved by the favorable vote of the ruling Socialist Party, the Left Bloc and People, Animals and Nature.
The law modified a similar one approved by the Legislative on September 15, 2009.