I can’t imagine that there is such a thing as the ACLU in Italia – I think an ACLU attorney would have a nervous break-down if they vacationed in Italia. Here the police do things many Americans would not believe, but are just considered part of bella Italia.
Everyone in Italia is required to carry identification with them at all times and theoretically you can be stopped on the street and be required to produce your identification. For an Italian or resident this would mean their carta identita, for a stranieri it would be your passport. Not being able to produce valid documents technically can result in your expulsion from the country.
In Italy there are various police groups. First there is the carabinieri, the state police, who many people seem to have a dislike for in their Armani uniforms and black and white cars. Then there are the polizia which are local police. We have seen both polizia and polizia municipale. There is also the corpo forestale who I believe deal with the park areas. There is even a guardia di finanza who are responsible for tax collection and it has been reported that they can stop you outside a store or bar and require you to produce a receipt for your purchase, if you can’t then you and the merchant can be subject to fines.
On our first visit to Italia we were surprised by the presence of police in the airports with machine guns and this was several years before 9-11. Italia however, has a long history of internal violence that Americans would find shocking with various groups having planted small explosive devices in public places in major cities and the kidnapping of government officials.
When driving in Italia you can be subject to random traffic stops and there need not be any reason that you are being stopped. The various police will set-up along the side of the road and stand on the side with a little white wand with a red circle. If they point this your direction you must pull over and present your documents and well as those for the car. Many times the officers will be wearing bullet proof vests with a small machine gun slung across their shoulder. We have been stopped on a couple occasions at these and usually when they realize we are straneri we are waved off.
We have never felt threatened by the police presence nor do we feel unsafe in any parts of Italy. In fact we feel safer in the center of cities like Roma at night than we would in most major US cities.