Greetings...I worked for prehomeland security as an officer and now i work with law firms on their border crossing cases...I can give you some insight on your case. First of all...what N category...were you under? I am going to assume it was either Management Consultant or Sciencetific Technician/technologist. These are the two professions that they hate with a passion. They feel that there is so much fraud with these two specific professions. Often, people attempt to qualify under these categories when they are not qualified at all(No reflecting on you).
Anyway, some of the posts were incorrect. They can indeed deny a
TN for any reason. they can and do make up reasons all the time. it is purely officer discretion and absolutely no guarantee or approval. Some of the newer CBP officers decide how long the feel that a person should be on a TN. if he or she feels that it has been too long...then they will indeed revoke/fail to renew it.
Once you do have a revocation...it will stay on your record. When you are entering the U.S ...their TECS database will show a lot of specific data that they use to process individuals.. They have a variety at their disposal like TECS, APIS, NCIC, CIPIC...etc..
Be very careful when they start alleging that you worked illegally...What you say can indeed be used against you.
Also, technically the field manual says that lawyers are not allowed to be present during inspections....but...they can and do make exceptions for certain lawyers as a "courtesy" to the applicant. it is dependant on the officer, what time of day it is and what day of the week. These guys have a tremendous amount of discretionary power. Also, if they did revoke it(and shouldn't have), the other officers tend to not want to go against another fellow officer and restore it. it will depend on whom you dealt with. There are about five officers at the Blaine border who are notoriously strict with Canadians. I believe that you may have had one of these.
Anyway, let me know if I can render aassistance.
usaimmigration@hotmail.com