Do I have to pay traffic fines issued by foreign governments?

Bringing a car with you is just not worth it; you would have to pay ~USD 1800 (Well that's East coast->Rome, in the other direction rates might be different, but depends on the size of the car, dates etc.), and this does not include import taxes and all the hassle you will have at customs. For the same amount of money you could as well buy a used car in the states and then sell it at the end of your travels. See also Shipping my car from Europe to the U.S.

For the traffic fines part: I spent a year in Australia and got a parking ticket ~1 month before i left, but never paid for it. From what the locals told me they usually don't care about tourists unless they rack up a few grand in fines or do something dangerous, such as speeding. Different thing in New Zealand, they might ask you for any fines you owe them on the Airport before your can leave the country - even locals who just want to go on a overseas vacation.

Of course if you bring your own car to the US they could just impound it until you pay the fines. Also, the police there seems to be generally much less tolerant towards traffic violations.

Do I have to pay traffic fines issued by foreign governments?

Yes, that's the law.

Next year I'm planning a long stay in the US (around 6 months) and I want to bring my car with me.

This is a whole other question, so I'll take it instead as a factor in your main question rather than go into the pros and cons of shipping a private vehicle.

If your aim is to avoid the consequences of breaking the law then breaking it in a vehicle easily traceable back to you will make it harder to dodge.

I was wondering, can I abuse carpool lanes, not pay parking spaces, break the speed limit etc etc with no consequences (while still driving safely ofc)?

There are prescribed consequences for breaking each of these regulations and those will definitely vary from state to state and quite possibly even from city to city. Some places are known to fiercely apply these rules or have periodic crackdowns. You will surely be in more trouble for things you are pulled over for than for things you find a ticket on your windshield for.

In any case this is a vast question about which entire books could be written, which makes it not a good Stack Exchange question.

If they give me a fine, is it just trash paper or can they somehow force me to pay?

I'd say it's a legal document but I'm not a lawyer. If you decide to treat it as trash paper you cannot expect us to condone such an action. Whether they can force you to pay surely will depend on many factors and is again too broad to try to answer here.

(What I want to avoid is basically going back to the US 20 years from now and getting arrested for that, or something similar)

To avoid future negative consequences 1. Don't break such laws or 2. Be accountable if you do break the law and pay the fine.

Yes you are obligated to respect the law. No judge will accept the fact of you being a foreigner. "Ignorantia juris non excusat" applies. There seems to be some exceptions to this judicial principle in the US, but they apply to tax laws, see Wikipedia article for details.

Your own country is even exploiting this requirement by inventing unreadable traffic signs, like "ZTL", which no foreigner will understand, but was invented against non locals. The penalty was enforced by local enforcement from my country of residence. I tried to explain that they can't expect me to understand ZTL, but apparently if you go to a country you need to understand the full consequence of the law. Now I know it means Zona traffico limitato, meaning that you are not allowed to drive there if you are not local.

First off, I can't comprehend how anyone in their right mind would even consider doing something like this -- shooting yourself in the foot is not illegal, and you are free to do so if you so choose, but actively endangering other people's lives strikes me as.. how do I put it more politely -- idiotic.

I can assure you that such kind of behaviour will not be looked kindly upon in a number of countries:

• In Sweden, there is zero tolerance towards breaking traffic laws. To get a good idea what kind of zero tolerance we're talking about -- parking fines start from $40-$50, you risk losing your license for 15 km/h over the legal limit in city areas, might get arrested for it, and even if you don't, the fine will be in the $1000s range.

  There are a number of cameras installed on the Swedish road network, they are completely automatic, and people receive their fees at home, with no but's or if's. Trust me when I say it that they don't miss an opportunity to make someone's life miserable.

  If you are stopped on the customs for any reason (regardless of Sweden being in EU, cars with non-Swedish plates are stopped sometimes for random checks), they will find out you've been having fun, and will not allow you leaving the country.

• Pretty much the same story happens in Bulgaria. The customs stop more cars than in other EU countries (partly because Bulgaria borders with non-EU states), and I know for a fact that you must pay your fines before you'll be allowed to leave. They might even impound your vehicle and force you to go back to the area where you violated the law and pay the fine there. Tickets do not expire really until they are paid, and although they are sometimes lax with the locals as long as they don't leave the country with their vehicles, they won't be very sympathetic to your cause.

First, as long as you stay in the US, you are subject to US laws. The US can (and will) fine or arrest you if you violate US law. I believe that in the US even minor offenses can theoretically go up to a jail sentence (e.g. $100 fine or 3 days in jail). If you commit a traffic offense and try to leave the country without paying the fine, the US government would have the right to detain you for that traffic offense. And they could add a charge of attempting to evade the penalty. So you might find that your stay is longer and less comfortable than expected.

Will you get arrested if you try to evade a fine? Maybe, maybe not. The US bureaucracy tends to be a little more efficient than the Italian one, but that doesn't mean that the US customs will know about your traffic fine when you leave (especially as the US government spends more on checks of on people who're entering than on people who're leaving). If you have an outstanding fine, they are very unlikely to pursue you outside the US.

If you owe any money to the US government, it's rather likely that they will not let you in later. This isn't just about traffic fines: you'd better pay your taxes, too. (Given the US tax structured, if you earn wages there, you'll probably be entitled to a refund; but if you earn money through other means make sure to leave a forwarding address to the IRS and applicable local authorities if you ever intend to return into the country.) The US immigration check includes a trawl of various databases that you might be in. That includes outstanding warrants and fines, as well as taxes. This is not a low-probability threat; US immigration officers have been known to google your name, not like something you did 40 years ago and deny you entry even though you what you did was legal. You may not use the visa waiver program (ESTA) and may be denied entry altogether; see for example the US embassy in Japan website and the US embassy in Ireland website and a non-official site.

The situation is similar in other countries, except that it's not so common that minor traffic offenses can result in your arrest. (Repeated failure to pay a fine usually does, though.) Some countries have specific provisions in their visa grant that you can be prevented from leaving the country if you have outstanding debts, so check the fine print. And do generally expect to have a hard time getting a visa again if you leave with outstanding fines.

Moving out of a country does not make you untouchable. Many local governments now employ debt collection agencies to track down and collect long overdue fines.

Debt collectors pay no attention to jurisdiction. All they care about is getting their commission upon collecting the debt. Chances are very good that several months or even years after you have moved back to Italy you will receive a bill in the mail and/or phone calls demanding payment for the long ago traffic fine in a faraway land.

If you ignore these notices, your credit rating could be damaged if the debt collector reports your overdue fine as a bad debt to the major credit reporting agencies. A debt collector based in your country can take any means permitted by your local laws to collect the debt, including placing liens against your property among other things.

The larger your overdue fine, the more enthusiastically the debt collectors will pursue you. Think a $100 parking ticket is too small to bother with? Think again. A $100 parking ticket caught up with me 8 years later, in another country and after several moves.

Consider what happens when you blow off that ticket:

When you fail to show up at court or pay the ticket a warrant is issued for failure to appear. The next time the cops stop you it won't be a ticket, it will be a trip to jail. (And, yes, they really do that. I know someone it happened to--she thought her mother paid the ticket. She was IIRC 16 at the time and spent some hours in jail before her mother bailed her out.)

Another thought on this, with regard to parking offenses. Sometimes they use boots to ensure you pay your fine. Your car isn't going anywhere until you pay up and they take off the boot.

In most states in USA, the statute of limitations for a fine is 10 years, which means that the fine stays active up to 10 years. USA does not have any bi-lateral agreement with any European country to enforce a ticket issued here in the states. However, in most states we have a system where we link any prior vehicle that you owned in the past (during those 10 years) and owes a fine with any vehicle that you own now in the present, the vehicle that you now own, it could be impounded even though you never got a fine on it.

My Italian office-mate of long ago used to show his Italian license when stopped for speeding, which was often. Usually the cop didn't bother. (I did this in reverse once in Israel, where I had missed a stop sign.) But once the policeman offered him the choice between paying the fine on the spot or going to court for the rest of the day, and paying the fine seemed better.

One small benefit is that the ticket I got overseas did not count against my USA license for insurance surcharge purposes.

Let's say that you get a ticket and manage to leave the country (with your car, no less), before they catch up with you.

A record of both the original violation and the unpaid fine (a second offense) will be kept by the country if their information systems are at all up to date. The next time you apply for a visa to that country, or try to enter with a passport, you will likely be "tagged" with the record of the offenses. The consequences could be denied entry into the country (e.g. at the airport), at least until you pay your fine, and possibly longer. Or you could be arrested upon trying to enter the country.

So pay your fines unless you have no intention of ever returning to that country again.