The most recent example came on March 12, when James R. Clapper, director of national intelligence, told the Senate Intelligence Committee that the government was not collecting information about millions of Americans. He later acknowledged that the statement was “erroneous” and apologized, citing a misunderstanding.

On three occasions since 2009, top Justice Department officials said the government’s ability to collect business records in terrorism cases is generally similar to that of law enforcement officials during a grand jury investigation. That comparison, some lawmakers now say, signaled to them that data was being gathered on a case-by-case basis, rather than the records of millions of Americans’ daily communications being vacuumed up in bulk.

In addition, two Democratic members of the Senate Intelligence Committee say that even in top-secret briefings, officials “significantly exaggerated” the effectiveness of at least one program that collected data on Americans’ e-mail usage…

“The national security state has grown so that any administration is now not upfront with Congress,” said Rep. Jerrold Nadler (D-N.Y.), a senior member of the House Judiciary Committee. “It’s an imbalance that’s grown in our government, and one that we have to cleanse.”