A RAND Corp.study concludes that personal data collected by fitness trackers and smartphones can compromise individuals' rights when used in legal proceedings.The legal system has not yet contemplated the implications such data could have, the study says.

Personal devices increasingly detect and record information on location, travel, heart rate, activity levels, and other aspects of our lives.This data is forming a bigger and bigger part of criminal investigation and prosecution.The technology greatly expands law enforcement's ability to conduct investigations, but it raises questions about constitutional rights related to privacy, unwarranted search and seizure, and self-incrimination.

Technology like teleconferencing may make it easier and more cost-effective to run trials, but it is not clear that such virtual trials afford defendants the constitutional right to confront accusers that they enjoy in proceedings where everyone appears in person.

"When changes are gradual, the law and the criminal justice systems have time to react and adapt naturally as conflicts appear," said Brian Jackson, a RAND scientist who served as lead author of the study. "But new technologies are developing rapidly and are likely to create conflicts before the legal system is fully prepared to deal with them."

RAND says law-enforcement agencies and courts must proactively analyze the effects of modern technology on constitutional guarantees.Once guiding principles are identified, they must be translated into tangible rules and procedures, and then communicated widely to prevent abuse.