Venice- pass port

Put your passport (and credit cards) in a place where they cannot be pick-pocketed.

Authorities can request that you produce your actual passport at any time. Not sure what happens if you are only able to produce a copy.

You might try using a money belt tucked under your waistline to carry your passport. It’s always worked for me.

Carry your passport in a money belt or buried deep on your person
Required by law, it is your official ID

Pickpocketers don’t want your passport
They want your cash and your phone

You can read thru all the previous posts regarding this issue
https://search.ricksteves.com/?button=&date_range=1y&filter=Travel+Forum&query=Passport+

I never walk around town with my passport. I leave it in the hotel safe, no matter where I'm visiting in Europe (and also South America when I go). I take picture/color photocopy and keep it with me, as well as on my phone. I carry my US Drivers' license also, which, in case of theft or loss, would be easier and faster to replace than the passport.

The chances you will be asked to show your passport in the streets are very low. The only place where you might be asked is the train station, and while driving if pulled over (police random road checks are very common in Italy). Although the last time I was pulled over (I get pulled over every year), I gave them my California DL and my IDP, and when I asked if they wanted my Italian national ID they told me no, that the California license and IDP was sufficient.

If you take a day trip out of Venice (for example to Padua), then you might be asked for documents by police at the station or on the train. Lots of antiterrorism checks on trains these days. However nobody will jail an American tourist for having left their passport in the hotel safe while walking around or going to the beach (never seen someone swimming with a passport pouch under their speedo). They have bigger fish to fry with the huge surge in petty crime (pickpockets) with the massive amount of tourism that has hit Italy after Covid.

However you will certainly have your passport with you when you arrive to the town and when you depart the town. So for those circumstances, since you will be very vulnerable due to the fact that you will be probably encumbered by luggage, it is best to secure your passport in an under garment pouch, as suggested above. Then if you also want to walk around town with it, you can use the same pouch.

Do not lose your passport (or get it stolen), because, although a US consulate can give you a temporary one quickly, however there is no US consulate in Venice. The closest one is in Milan or Florence. So that would be a major waste of time and money (and you would still have no passport while traveling to the closest US consulate).

Thank you Roberto. I appreciate the perspective.