Here’s an annotated analysis of Mr. Zuckerberg’s post and what he is seeking to do with each area.

Harmful Content

First, harmful content. Facebook gives everyone a way to use their voice, and that creates real benefits — from sharing experiences to growing movements. As part of this, we have a responsibility to keep people safe on our services. That means deciding what counts as terrorist propaganda, hate speech and more. We continually review our policies with experts, but at our scale we'll always make mistakes and decisions that people disagree with.

So-called harmful content across Facebook is an enormous category, spanning abuse and bullying to the recent live-streamed shootings at two mosques in New Zealand. With more than 2.7 billion people regularly using Facebook’s services, policing such content is far and away the most difficult issue facing the company.

By saying that “Facebook gives everyone a way to use their voice,” Mr. Zuckerberg makes something clear: The social network’s sheer size means there will forever be errors, mistakes and things that it misses. Tens of billions of posts are shared to the network every day, making it impossible to keep the platform clear of harmful content.

Facebook has had a difficult time deciding what is and isn’t allowed on its site. Its policies often seem to be defined by its most extreme cases, which often spur outrage when handled poorly by the company’s content moderators.

If Facebook’s policy determinations will always cause dissatisfaction, then it may be better to leave it up to lawmakers to write the rules for it. By adhering to the letter of the law, Facebook can effectively shield itself from blame when something inevitably goes awry.

Election Protection

Second, legislation is important for protecting elections. Facebook has already made significant changes around political ads: Advertisers in many countries must verify their identities before purchasing political ads. We built a searchable archive that shows who pays for ads, what other ads they ran and what audiences saw the ads. However, deciding whether an ad is political isn't always straightforward. Our systems would be more effective if regulation created common standards for verifying political actors.

For years, Facebook has maintained little oversight over its political advertising practices. The company raked in revenue by the billions of dollars on the back of its automated advertising system. Wall Street loved Facebook’s reliable blockbuster financial results and the company’s stock soared.