Q: Is short-term travel on an ESTA visa in the US allowed while I am waiting for approval of my I-485 visa application?

A: Using your ESTA to try to visit your husband will not have any effect on your CR1 case per se (that is, there's nothing illegal about it). However, there can be some complications. The biggest risk is that if you travel to the US on ESTA while the CR1 case is pending, you might be denied entry to the US. The reason is that those seeking entry to the US on ESTA must have the intent of returning to their home countries. The CR1 case is essentially viewed as a manifestation of your intent to reside permanently in the US. I have seen people travel successfully to the US on ESTA, tourist visas, etc. while permanent resident applications are pending, but entry to the US is ultimately decided by the officer at the port-of-entry. Much would depend on the particular officer you get. I generally recommend trying to avoid travel to the US on ESTA once an I-130 has been filed if possible. If not, make sure you can demonstrate to US immigration officials that you intend to return to Europe. Documents such as lease agreements, proof of employment, etc., will help in that regard. Should you ultimately be denied entry, request that you be permitted to "withdraw your application for admission" rather than receiving an expedited removal order. The latter will have an adverse affect on your CR1 case, whereas the former would not.

A: Technically, you should be able to travel to the US. You will likely need to show a great deal of evidence that you plan to return home at the end of temporary travel—work, school, assets, family, other factors.