Twitter rejected four advertisements from the Center for Immigration Studies (CIS) on the basis of the tweets containing “hateful content” on Tuesday. The hateful content in question appears to be the phrase “illegal alien.” The platform later reversed the decision, calling it an “error.”

The CIS tried promoting several tweets through Twitter’s advertising program. Below are the CIS tweets labeled “hateful content” by Twitter:

A new video from the @DailyCaller showing illegal aliens pouring across the border reminds us why we need a wall. Technologies and adequate manpower are well and good, but the best defense is always to prevent individuals from entering in the first place.https://t.co/wfWInr9RWf — Center for Immigration Studies (@CIS_org) September 10, 2018

A couple in Oregon was recently killed by a drunk-driving Mexican illegal alien. Now, with the state’s sanctuary law being put up to a ballot, the sanctuary law’s defenders say the other side is “seizing upon” illegal alien crime. Isn’t that the point?https://t.co/lScfW32pUm — Center for Immigration Studies (@CIS_org) September 10, 2018

The farm which employed the illegal alien who killed Mollie Tibbetts was raided by ICE agents. ICE should do more of this– continue to focus on employers of illegal aliens who commit serious crimes. Often, those arrests lead to many more aliens found.https://t.co/Ht0vHneeIo — Center for Immigration Studies (@CIS_org) September 11, 2018

ICE recently completed a massive multi-state enforcement operation targeting criminal aliens that resulted in the arrests of 364 individuals. Of those, 187 (51%) had prior criminal convictions and 97 had been previously removed from the United States.https://t.co/PSWsBNlmCU — Center for Immigration Studies (@CIS_org) September 6, 2018

In response to a CIS inquiry, Twitter’s customer service stated it had manually reviewed and reaffirmed its rejection of CIS’s requested promotion of the aforementioned tweets:

We’ve reviewed your tweets and confirmed that it is ineligible to participate in the Twitter Ads program at this time based on our Hateful Content policy. Violating content includes, but is not limited to, that which is hate speech or advocacy against a protected group.

In its initial comment on the matter, CIS indicated it was the use of the term “illegal alien” that Twitter considers hateful, despite the common usage of the term by legal entities including the Supreme Court.

Twitter CEO Jack Dorsey maintains that his company’s censorship and content management policies are not colored by left-wing or partisan Democrats biases.

Update — After this article was published, Twitter reversed its decision, and called the decision to label “illegal alien” as hate speech an “error.”

Follow Robert Kraychik on Twitter.