That has been on my mind too. The 4th and 5th Amendments seem to be all but dead now. Hopefully a significant percentage of the population would consider a "Shelter In Place" order for gun confiscation to be a more dangerous reason and immediately take action to make it more dangerous. By an order of magnitude.
Orin Kerr over at The Volokh Conspiracy started a discussion about this
House-to-House Searches and the Fourth Amendment
http://www.volokh.com/2013/04/19/house-to-house-searches-and-the-fourth-amendment/