There's no such thing as this.
Honestly, is everyone these days completely ignorant of what happens when you leave a few rotten apples in a big bunch of apples? In case you don't know, the correct answer is that very soon, ALL the apples become rotten. That's why we have the old saying about "bad apples": "one bad apple ruins the whole bunch". Somehow, these days, everyone seems to have forgotten the "ruins the whole bunch" part of the phrase which is so important to its meaning.
It applies outside of apples too: it applies to police, corporations, any human organization really. There's no such thing as "only a few bad apples". An organization that tolerates rotten people very quickly becomes thoroughly rotten.
Next, deputise an ombudsman to whom every employee has a confidential and direct line. This ombudsman reports directly to the CEO and the Board. They should have a large amount of authority surrounding recommending dismissal of any employee to the CEO; whenever a recommendation is made, it should be copied to the Board. In return, the ombudsman should carry a significant amount of personal liability in connection with sexual harassment at the company.
This is how compliance works at many financial firms, and it's very effective. Compliance officers are deputized by the U.S. Treasury for anti-money laundering purposes. This makes them personally responsible if something goes wrong. It shows.
How about firing sexual harassers? And any HR staff that systematically lied to cover it up. And the people who gave them those orders. And not taking forever to do it.
Usually these are handled with a shake-up at the top, and other involved people being let go.
Lot of people have suggest these problems stem from the culture. Culture of companies and people is similar to the culture of, say, bread. The starter really matters and sets the tone. I'd be interested in hearing from people who have seen a drastic change in culture at a big place or better yet, have been behind that change.
The other idea is it could just be a few rotten apples giving everyone a bad name. I don't know the answer.