The ban on political ads announced by Twitter two weeks ago has come into effect, and the rules are surprisingly simple — perhaps too simple. No political content as they define it may be promoted; candidates, parties, governments or officials, PACs and certain political nonprofit groups are banned from promoting content altogether.

The idea intended to be made manifest in these policies is that “political message reach should be earned, not bought,” as the company puts it. It’s hard to argue with that (but Facebook will anyway). The new rules apply globally and to all ad types.

It’s important to make clear at the outset that Twitter is not banning political content, it is banning the paid promotion of that content. Every topic is fair game and every person or organization on Twitter can pursue their cause as before — they just can’t pay to get their message in front of more eyeballs.

In its briefly stated rules, the company explains what it means by “political content”:

We define political content as content that references a candidate, political party, elected or appointed government official, election, referendum, ballot measure, legislation, regulation, directive, or judicial outcome.

Also banned are:

Ads that contain references to political content, including appeals for votes, solicitations of financial support, and advocacy for or against any of the above-listed types of political content.

That seems pretty straightforward. Banning political ads is controversial to begin with, but unclear or complicated definitions would really make things difficult.

A blanket ban on many politically motivated organizations will also help clear the decks. Political action committees, or PACs, and their deep-pocketed cousins the SuperPACs, are banned from advertising at all. That makes sense, since what content would they be promoting other than attempts to influence the political process? 501(c)4 nonprofit organizations, not as publicly notorious as PACs but huge spenders on political causes, are also banned.

There are, of course, exemptions, both for news organizations that want to promote coverage of political issues, and “cause-based” content deemed non-political.

The first exemption is pretty natural — although many news organizations do have a political outlook or ideological bent, it’s a far cry from the practice of donating millions directly to candidates or parties. But not just any site can take advantage — you’ll have to have 200,000 monthly unique visitors, make your own content with your own people and not be primarily focused on a single issue.

The “cause-based” exemption may be where Twitter takes the most heat. As Twitter’s policy states, it will allow “ads that educate, raise awareness, and/or call for people to take action in connection with civic engagement, economic growth, environmental stewardship, or social equity causes.”

These come with some restrictions: They can only be targeted to the state, province or region level — no ZIP codes, so hyper-local influence is out. And politically charged interests may not be targeted, so you can’t send your cause-based ads just to “socialists,” for example. And they can’t reference or be run on behalf of any of the banned entities above.

But it’s the play in the definition that may come back to bite Twitter. What exactly constitutes “civic engagement” and “social equity causes”? Perhaps these concepts were only vaguely defined by design to be accommodating rather than prescriptive, but if you leave an inch for interpretation, you’d better believe bad actors are going to take a mile.

Clearly this is meant to allow promotion of content like voter registration drives, disaster relief work, and so on. But it’s more than possible someone will try to qualify, say, an anti-immigrant rally as “public conversation around important topics.”

I asked Twitter whether additional guidance on the cause-based content rules would be forthcoming, but a representative simply pointed me to the very language I quoted.

That said, policy lead at Twitter Vijaya Gadde said the company will attempt to be transparent with its decisions on individual issues and clear about changes to the rules going forward.

“This is new territory,” she tweeted. “As with every policy we put into practice, it will evolve and we’ll be listening to your feedback.”

And no doubt they shall receive it — in abundance.