1. On two the travel days included in the Interrail pass, you can also travel in your country of residence.
2. No limits indeed for Eurail. Does he also have a German passport, or not? If in possession of a German Passport (dual nationality) he cannot use the Eurail passes:

https://www.eurail.com/en/help/interested-in-eurailing/do-i-need-a-eurail-or-an-interrail-pass

Thx for the quick reply. No, he does not have a German passport. So I assume, 2) will apply and the Eurail ticket would be what will help him. :)

Inspectors on trains are only concerned that a passenger has a valid pass (and reservation evidence for trains with mandatory requirement). If his Eurail pass shows he is a US citizen then, if queried, he simply shows his US passport, which he will of course have used for travel across borders. For Eurail pass users they do not require any further evidence.

The Eurail pass has no restrictions on which countries he can travel in.

Hi all, 

It is important to point out that in all circumstances, the residency is what counts, even though it is unlikely that the inspector will ask for a residence permit and only the police can actually check the entry stamp on the passport of travellers. This is due to the agreements with the railway and the fact that the Pass is meant for travel outside of your country of origin/residence.

It is crucial to remind that this information is clearly stated on the Conditions of Use of our Passes that can be found here, with a clause 2.3 Country of residence.

Have a nice evening!

@Camilo.  Then i will ask how should i proof my foreign residency? You not always get a Residency card or a paper of your registrated residency ;) 

I lived in the UK (when they still were in the EU) and in Finland and never had a residency card or anything that said yes iam liveing there. The only thing i could show were my Bank account with the withdraw of my Rent for my Appartment there. 

In my opinion this part in the Condition of Use have to be more precise. I had several tours with US Citizen that lived in Europe (Italy,Germany, UK in the military garnisions) and had always problems when we used Interrail with the Country they were based in as Country of Residence. But showed them the US Passport as ID docoument. When we swtiched to Eurail Passes there was finally never a problem anymore and yes even as it´s against the Condition of Use that´s what were told us by Customer Service of several Railcompanies for the future to avoid any problems with the conductors on the trains. 

I know it´s not your fault but some rules regarding Interrail & Eurail are not actual anymore and should be revised and maybe renewed :) 

Dear @seewulf 

I agree that this has to be more specific, however as you pointed out, they typically don't verify the documentation of Eurail Pass holders, thus it's practically hard to follow the rule.

To answer your question on how to proof residency, AFAIK, European citizens are obliged to register their residence with the relevant authority (town hall or local police station) after 3 months. Info here: Registering your residence abroad - Your Europe (europa.eu)

Of course it is very improbable that you are carrying with a copy of your residence confirmation, but I guess this would be the proof you are talking about. 

Happy easter!

In your link it says 
After 3 months in your new country, you may be required to register your residence with the relevant authority (often the town hall or local police station), and to be issued with a registration certificate.

And i was never required to register my new residence. Ofcourse as i worked there i had to pay taxes in these Countries means i could show my Taxpaper :D 
Again i never had a residence confirmation of the Cities were i lived. 

A purely pragmatic view but I am sure if you have a passport it will satisfy any inspection, so, irrespective of how long you have resided in any other country you could claim your country of citizenship as your country of residence for train inspection of a Eurail or Interrail pass, especially if you are using that passport for border control.

Yes. But Camilo insisted on the Condition of Use. And i just wanted to know how future travelers could proof their residency. 

When you are out of the tracks and use your Citizenship (Passport) as Country of residence it will never be a problem. But how about e.g. a German Liveing in Finland or any other EU Country. and trying to use that Country as Country of Residence how is he supposed to proof it. You net always have to registrate at the townhall. e.g. when i lived in Finland i only had my “deregistration” from Germany but never were registrated in Finland :D

I just wanted to point out that this rule is not very clear and the Country of Residence is a difficult term. 

I understand your point, but there is a (pragmatic) difference between “official” proof of residence and the reality of a rail inspector who only wants to check you are not travelling without a valid ticket. In most cases he is only likely to be suspicious that you are not the person named on the pass. In a very rare case he may suspect you are trying to use it in your COR for more than the permitted Interrail 2 COR days, as that is the only restriction on an Interrail pass. (OOI the mobile app manages this diligently against your declared COR if you have an Interrail pass).

If you are, for example a resident of Belgium travelling in Holland an inspector may confuse Flemish and Dutch and ask for ID with proof of home address. Assuming your pass is valid, he is almost certain to accept any “credible” evidence of residence even if it isn’t on an official list - bearing in mind that a universal list doesn’t exist anyway.

I have seen advice that if you have citizenship outside Europe but living in Europe without a relevant ID you should use your citizenship as your COR - This could also be done by a European Citizen temporarily living in another European country, but then they would be limited to 2 days travel in the country they register their pass.

 

Dear @seewulf 

I have found this regarding Finland: 

“If you are planning on staying in Finland for more than three months, you must apply to the Finnish Immigration Service (Maahanmuuttovirasto) for the registration of an EU citizen’s right of residence. The application must be submitted within three months of the day of arrival at the latest.”

EU citizens (infofinland.fi)