The National Academy of Sciences moved this week toward a landmark shift in policy that would allow it for the first time to eject members who have violated its code of conduct, including in cases of sexual harassment.

The group’s members, who include some of the world’s most prominent scientists, are elected to lifetime positions, and currently they can only be asked to depart.

But as the science world moves to address gender imbalances, discrimination and sexual harassment against women in historically male-dominated fields, the academy has faced pressure to change its membership rules.

In a preliminary vote on Tuesday at the group’s annual meeting in Washington, members approved an amendment to the organization’s bylaws that would give it the power to remove any scientist who engages in sexual harassment, discrimination, bullying or other activities as defined in a new Code of Conduct.