During a discussion with someone who happens to be a dual British/US citizen, he maintained (quite heatedly in the face of my disbelief) that an American lawyer who specialized in immigration told him in no uncertain terms that if he tried to enter the US using a British passport, this would be taken as an automatic renunciation of his US citizenship. Everything I have heard on the subject of renunciation has been that there is no renunciation without intention and that this has been accepted law for at least 25 years after the State Dept. lost a number of cases on the subject. He asserted that he had been assured of this within the last ten years and the lawyer was adamant on the fact. The only counter I have is that an American immigration lawyer has no occasion to deal with Americans and may well not be up on the situation. Does anyone know a definitive answer.
Incidentally, I am a dual (US/Canadian) citizen. So this is of more than academic interest to me.
Although these answers are correct, they don’t really answer the question. When the Dept of State says “Most U.S. citizens, including dual nationals, must use a U.S. passport to enter and leave the United States.”, I think they mean that it is illegal for most US citizens, dual or not, to enter the US using a foreign passport. What we don’t know is what is the likely consequences if you are caught. Automatic loss of citizenship certain seems rather harsh. I would hope that someone in the process would consider the circumstances. Did the person carelessly pull the wrong passport out of their bag without any bad intent or did they purposely use their “spare” passport in the hope of slipping in as a foreign visitor without being recognized.
Yes, the general rule is that you are supposed to use the passport of the country you are entering if you have one. There are several reasons. One of them is that you are not protected by foreign consular treaties. If you are a dual French-American citizen you are not entitled to French consular protection in America whereas if you are only French then you are. In other words each country considers you only citizen of their own country with all the privileges and restrictions.