I doubt you will find any of these responses helpful. As a general rule, the police can only cross the threshold of the home (ie a doorway) with a search warrant; an felony arrest warrant if the subject of the warrant lives in the house and it is his house; consent or exigency circumstances.
Based upon your limited description, it would appear the police believed they had exigent circumstances. For example, if they were responding to a domestic call (could have been placed by a concerned neighbor who heard shouting, etc.). Whether they acted reasonably is the issue.
If owner or renter of the property would ave standing to challenge this in court. Your friend should immediately contact a criminal defense lawyer. Once the criminal charges and ICE hold are resolved, he may wish to further explore the civil rights issues.
This response is provided for informational purposes only. It is not a consultation and is not legal advice. You should not act or fail to act in reliance upon the information provided in this response. This communication does not establish an attorney-client relationship between you and our Firm. You should always consult with an attorney prior to taking any action with regard to a potential legal problem.
The can, because they did. The question of whether it was appropriate depends on many more facts, and what they can do is hire a lawyer immediately rather than posting details on the internet. It does no good to post one side of part of the story (and second or third hand, at that). No response here will help him where he is.
The best thing that "the person" can do is hire an experienced criminal lawyer immediately. There may or may not have been a violation of constitutional rights, but whether there was or not he needs help.
No attorney client relationship has been, or is being formed as a result of this response to your question. If you feel you need legal advice, you are strongly encouraged to retain an attorney and consult with that attorney about this issue.
Respectfully, the police version of events is likely different. And even if I, or any other attorney tells you this was illegal, it won't matter. You need to hire an experienced defense attorney.