The specific rule the FBI is targeting outlines the terms for obtaining a search warrant. It's called Federal Rule 41(b), and the requested change would allow law enforcement to obtain a warrant to search electronic data without providing any specific details as long as the target computer location has been hidden through a technical tool like Tor or a virtual private network.
Everything my employer does is via a VPN. This little change would be carte blanche for virtually all corporate communications within the United States. Even the company's internal networks would be laid bare if they're remotely accessible. The opportunities for abuse are staggering.