In 2005 now retired Benton County Sheriff's Sergeant Michael Downing participated in an unlawful seizure at my residence in support of his partner Christopher Gore. The item in question was a computer that was not turned on and my lawyer later told me that plain view does not apply to computers because seeing a computer does not tell you what is on it. Plain view really applies to clear evidence of unlawful activity. Investigating the use of a computer to print documents that are allegedly illegal does not give the police the right to seize any computer that the observe in the home of the suspect. The proper procedure is to obtain a search warrant based on suspicion of that being the computer used to commit the offense being investigated.
A good example of plain view would be if I had invited them in and they noticed a giant marijuana plant growing in the living room. Even though they were not there for anything having to do with marijuana, seeing the plant in plain view would legally justify a seizure. The same cannot be said of a computer in a room because just seeing a computer in plain view does not indicate that it was used unlawfully at all.