Congress, however, generally disagrees with the executive branch’s expansive theory of presidential control over information. The two branches worked out a compromise that Congress passed as the Intelligence Community Whistleblower Protection Act in 1998 and amended in 2010 and 2014.

How can Congress get whistle-blower complaints?

That law sets up a special process that allows intelligence employees or contractors to provide information to Congress in exchange for protecting them from retaliation or the threat of reprisal. Under that procedure, they submit the complaint for lawmakers to the intelligence community’s inspector general.

Under the law, the inspector general must decide within 14 days whether the information is credible. The inspector general must also determine whether the allegations amount to an “urgent concern,” meaning they relate to a “serious or flagrant problem, abuse, violation of the law or executive order, or deficiency relating to the funding, administration, or operation of an intelligence activity within the responsibility and authority of the director of national intelligence involving classified information.”

If the complaint meets that standard, the inspector general is supposed to forward it to the director of national intelligence. The law says that within seven days of receiving the complaint, the director in turn shall forward the material to the House and Senate intelligence oversight committees.

Is that what happened here?

No. While the inspector general for the intelligence community, Michael K. Atkinson, told Congress that he had determined that the complaint was credible and qualified as an “urgent concern,” Mr. Maguire has refused to transmit it to Congress.

Can the whistle-blower do anything more?

The Intelligence Community Whistleblower Protection Act says that if the inspector general rejects a complaint as not credible or not presenting an urgent concern, the official who filed it may still then provide the information to Congress. But in order to continue to be legally protected from reprisal, he or she must obey directions from the director of national intelligence on how to approach lawmakers in a way that secures classified information.

That raises another loophole: The whistle-blower first must obtain specific directions from the director of national intelligence before he or she can obey them. Here, Mr. Maguire is apparently refusing to provide any, according to a House Intelligence Committee official.