For U.S. permanent residents, there are a variety of different situations that have the potential to raise immigration law issues. One is international travel.
Now, it is very important to note that U.S. green card holders are allowed to travel outside the U.S. Thus, international travel by such individuals doesn't automatically raise immigration problems. However, long or frequent travels outside the U.S. do have the potential to raise some concerns.
For one, special paperwork issues can come up in relation to long trips.
Also, international travel is one of the things that immigration law officials may look at to determine whether a given U.S. green card holder does intend to make America their permanent home. Long or frequent trips outside the U.S., depending on the circumstances, may be viewed by immigration officials as potential red flags that a green card holder may not have this intent. This can be a major issue, as being found to not have the intent to have America as a permanent home can lead to a green card holder losing their permanent resident status through a finding of abandonment.
Also, long trips outside U.S. could have impacts for U.S. permanent residents looking to become a U.S. citizen in the future. This is because long trips outside the U.S. could cause a person to not meet the continuous residency or physical presence requirements for seeking citizenship.
If a U.S. permanent resident is wondering if an international trip they are planning would trigger any potential immigration law issues, they should talk with a skilled immigration law attorney. Such lawyers can review a permanent resident's situation and travel plans, assess whether any potential immigration issue triggers are present and provide them with advice on how to proceed.
Source: U.S. Citizenship and Immigration Services, "International Travel as a Permanent Resident," Accessed Feb. 2, 2016