Hi,
I am Canadian citizen, I live and work in USA (Arkansas) as a
professional under TN visa. I have a common law spouse, she lives in
Italy, we have 4 year old son, lives with me. Can I apply to sponsor her to
Canada as a Common Law spouse and could my application be processed
while I am living and working in US?
She has 11 years old daughter from her previous marriage, that do not
intend to immigrate to Canada. I have canadian tax return for previous
year. Would appreciate your advise.

I applied (Sponsorship of Common Law Spouse and her application for
Canadian permanent residency (in Italy)) more than a year ago, (I lived in
Canada, Ontario at that time) and my application was returned, they
asked for medical exam of my Common Law spouse's daughter. Since then
I moved in US and do not know if I am still able to reapply. CIC phone
numbers work only within Canada and I am unable to contact them>
Thanks in advance.

Vlad,
This is just a free comment.  You may be interested in the Wikipedia
site on the subject:
http://en.wikipedia.org/wiki/Common-law_marriage#Canada

It seems as though an "unfriendly" authority could question the
validity of a common law union since you are not living together at
present, but I hope not.
Good luck, Myoarin