Authentic Assessment

Do you believe that authentic assessment is possible in every subject area? Can students at every grade level demonstrate mastery through authentic assessment? Why or why not? Is it practical to ask teachers to complete these types of activities in the current, high stakes testing environment?

I do believe that authentic assessment is possible in every subject area because all material they are learning should be applicable in some way to the child's learning. However, I don't think that authentic assessments i possible for every STANDARD as not all standards are written in such a way to allow for more rigorous or applicable assessments.  
I believe that students at every grade level can demonstrate mastery through authentic assessments provided the teacher has adequate time to create, teach, and administer those assessments, and the students are given quality time to respond to the assessments.  
Authentic assessment is the basis for inquiry learning.  So it is possible, just not probable given the handicapping environments most teachers/students must work within.