1) The case being talked about is USA v. Gould, and you can read it at
http://www.ca5.uscourts.gov/opinions/pub/02/02-30629-CV0.wpd.pdf.
2) As some other lawyers here have pointed out, the law announced here does not seem particularly startling.
The Supreme Court has said that a "protective sweep" (limited to checking spaces large enough to be hiding a person who might attack) is OK when the police are making an arrest;
the majority opinion says that the question here is merely whether a protective sweep may EVER be permissible when the police are properly in a home for other reasons.
3) The second dissent makes a strong argument that this case law invites the police to abuse it. The judge who wrote this opinion makes some very good points about "what really happened," and those points are arguments for a reconsideration of 4th Amendment case law; but the majority doesn't think they are making any great change to existing case law, and I think they are correct in that.
4) The fact that the 5th Circuit considered this case "en banc" (i.e. with all available judges) shows that they are considering these issues carefully. The hot dissent also shows that we have judges who are trying hard to make the right decision. This is a good thing.
5) As some cops and ex-cops here have pointed out, the "protective sweep" doctrine does address a real problem IF you're in the circumstance where cops are legally in someone's home.
6) For those who feel cautious, the practical moral is simple: Never, ever invite any LEO into your home at any time for any reason (except maybe close personal friends who are OFF duty). Be as polite as you feel like being, bring milk and cookies and chairs out onto your front porch if you want - but when you open your door to the government, you're opening it wider than you think. Tell your children, tell your friends.
Hope this helps. If you want something to be alarmed about, read about the California case where the cops got a drug search warrant based on high electricity usage. I think the real anomaly here may have been that the cops who served the warrant were commendably honest, or maybe they forgot to bring along a throw-down. From the facts stated in the news report, whoever signed the search warrant could not possibly have been shown any "probable cause." That sort of abuse happens all the time, and there is usually no way to correct it.
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