The F.B.I. director, Robert S. Mueller III, has argued that the bureau’s ability to carry out court-approved eavesdropping on suspects is “going dark” as communications technology evolves, and since 2010 has pushed for a legal mandate requiring companies like Facebook and Google to build into their instant-messaging and other such systems a capacity to comply with wiretap orders. That proposal, however, bogged down amid concerns by other agencies, like the Commerce Department, about quashing Silicon Valley innovation.

While the F.B.I.’s original proposal would have required Internet communications services to each build in a wiretapping capacity, the revised one, which must now be reviewed by the White House, focuses on fining companies that do not comply with wiretap orders. The difference, officials say, means that start-ups with a small number of users would have fewer worries about wiretapping issues unless the companies became popular enough to come to the Justice Department’s attention…

Instead, the new proposal focuses on strengthening wiretap orders issued by judges. Currently, such orders instruct recipients to provide technical assistance to law enforcement agencies, leaving wiggle room for companies to say they tried but could not make the technology work. Under the new proposal, providers could be ordered to comply, and judges could impose fines if they did not. The shift in thinking toward the judicial fines was first reported by The Washington Post, and additional details were described to The New York Times by several officials who spoke on the condition of anonymity.