In a rare public meeting that lasted less than five minutes, the House Ethics Committee approved a package of revised rules Wednesday designed to help streamline future investigations.

The changes also clarify standard operating procedure in cases where an ethics investigation heads into advanced stages, when investigative and adjudicatory subcommittees are convened and when a public “trial” might take place.

Two committee rules were revised to instruct “members of the Committee [to] engage in a collegial discussion” in the event the subject of an investigation formally objects to a lawmaker being appointed to either subcommittees tasked with overseeing the case.

Another rule states that an adjudicatory subcommittee may subpoena witnesses and testimony, and that a subpoena for documents “may specify terms of return other than at a meeting or hearing of the subcommittee.” The rules had previously bound the subcommittee’s subpoena authority with holding an adjudicatory hearing.

The rules will also now require the chairman of an adjudicatory subcommittee to “establish a schedule and procedure for hearing and for prehearing matters.” That must take place within two weeks or five legislative days of the appointment of members to an adjudicatory subcommittee, whichever comes later.

Though it is not uncommon for the Ethics Committee to revise certain rules as a legislative session draws to a close, most of these changes are influenced by “lessons learned,” according to Rep. K. Michael Conaway, R-Texas, who will become the committee’s chairman in the 113th Congress.

More specifically, they came about in the wake of the two major ethics investigations undertaken over the past few years. Already uncommon unto themselves, they were even more unprecedented for the ways in which they unraveled.

Rep. Charles B. Rangel, D-N.Y., who was ultimately censured on the House floor in 2010 for myriad House rules violations, decided to walk out of his public “trial.”

And California Democratic Rep. Maxine Waters’ case, which alleged that she used her influence inappropriately as a senior member of the Financial Services Committee, was delayed for almost two years and held over to the 112th Congress because of “new evidence” and battles within the staff ranks. It required an outside counsel to assess whether the investigation could even continue, and Waters was ultimately exonerated in September, with her chief of staff and grandson receiving formal admonishments.

More formal changes to how members and staff should be held to various ethical standards that are based on the Waters’ incident, such as stipulations about nepotism in hiring practices, could be part of a broader House Rules package for the 113th Congress.

An earlier version of this article misidentified existing Ethics Committee rules as ones that were recently added and misstated when an adjudicatory subcommittee can proceed with hearings.