I think its difficult to generalize on the possible actions of police based on actions after Katrina. New Orleans police were witnessed looting (stealing, a felony) from stores and hotels, not 'confiscating' anything for the greater good - there was no higher plan or greater good behind these acts, they were simple felony, carried out in broad daylight among civilian looters. From what I know of the NOPD, this was somewhat predictable, a good portion of the force has always been less than reliable and susceptible to open corruption, but not every NO officer is- or police departments generally. You splash a hurricane down on my part of the country and I betcha dollars to donuts that the same looting and stealing does not go on - and if it does, the cop gets the same treatment as any other looter.

Private firearms were also seized in New Orleans, especially after the first night of pitch darkness, reported rapes, looting, pillaging, assaults and murders. Martial law might have had a similar effect as seizing firearms, and the same intent - get guns off the streets. Here authorities did what they felt they had to do at the time to reduce violence - seizing guns would have a debatable impact, but for people who had few other options I could see why they did what they did.