A spending package expected to be approved as part of a deal to reopen the government would create a wide legal avenue for senators to sue for as much as half a million dollars each when federal investigators search their phone records without notifying them.

The provision, tucked into a measure to fund the legislative branch, appears to immediately allow for eight G.O.P. senators to sue the government over their phone records being seized in the course of the investigation by Jack Smith, the former special counsel, into the riot at the Capitol on Jan. 6, 2021.

The provision would make it a violation of the law to not notify a senator if their phone records or other metadata was taken from a service provider like a phone company. There are some exceptions, such as 60-day delays in notification if the senator is considered the target of an investigation.

The language of the bill states that “any senator whose Senate data, or the Senate data of whose Senate office, has been acquired, subpoenaed, searched, accessed, or disclosed in violation of this section may bring a civil action against the United States if the violation was committed by an officer, employee, or agent of the United States or of any federal department or agency.”

Because the provision is retroactive to 2022, it would appear to make eligible the eight lawmakers whose phone records were subpoenaed by investigators for Mr. Smith as he examined efforts by Donald J. Trump to obstruct the results of the 2020 presidential election.