For starters, Twitter’s policies leave plenty of gray area.

According to its rules, Twitter may suspend an account for a number of reasons, including if the user makes violent threats; attacks people based on race, religion, gender and more; or engages “in the targeted abuse or harassment of others.”

If Trump’s tweets about Brzezinski are at risk of violating any part of this policy, it would likely be the rules against harassment. But here it may be useful to compare Trump’s Twitter behavior to another high-profile account: Martin Shkreli.