Twitter rejected four tweets from a Washington-based immigration research center’s advertising campaign as “hate speech” Tuesday because they used the legal terms “illegal alien” and “criminal alien.”

The rejected tweets by the Center for Immigration Studies, proposed for its Twitter Ads campaign to attract more followers, generally provided a statistic or factual statement and pressed for an immigration-related policy.

One tweet included a video from The Daily Caller news organization depicting immigrants illegally crossing the border and said the video “reminds us why we need a wall” and “the best defense is always to prevent individuals from entering in the first place.”

Another rejected tweet from the Center for Immigration Studies referred to a news story about arrests made by U.S. Immigration and Customs Enforcement and provided a statistic:

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 a press release Wednesday, the immigration research group said Twitter approved “several other” tweets for the Twitter Ads campaign. When the center asked why the social media company had rejected the four tweets, it said it received this response from the company:

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.

The immigration center said its motive was “to promote specific tweets in order to drive traffic” to its website, not to violate Twitter’s “Hateful Content Policy.”

The term “illegal alien” is a precise term in law, Hans von Spakovsky, a senior legal fellow at The Heritage Foundation, wrote in a recent commentary for The Daily Signal decrying politically correct language about illegal immigration such as “undocumented immigrant”:

‘Alien’—rather than ‘immigrant’—is the correct legal term, since ‘alien’ is defined in 8 U.S.C. §1101 (a)(3) as ‘any person not a citizen or national of the United States.’ Precision in the law is a vital principle, since the exact words used in statutes, regulations, contracts, guidance documents, and policy statements can significantly affect how they are applied and interpreted.

>>> Commentary: ‘Undocumented Immigrant’ Is a Made-Up Term That Ignores the Law

Twitter did not respond to The Daily Signal’s request for comment.

Marguerite Telford, communications director at the Center for Immigration Studies, said in the group’s release: