I am not an Objectivist, but I liked this: http://www.theobjectivestandard.com/blog/index.php/2012/06/political-left-and-right-properly-defined/
The proper purpose of government is to protect individual rights by
banning the use of physical force from social relationships and by using
force only in retaliation and only against those who initiate its use. A
properly conceived political spectrum must reflect this fact. Whatever
terms are used to identify the positions of political ideologies or
systems must be defined with regard to the fundamental political
alternative: force vs. freedom—or, more specifically, rights-protecting
vs. rights-violating institutions.