Consider these two scenarios:
1. A parent tells his teen: "No drinking. And be home by midnight."
2. Another parents tells his teen: "Be safe tonight. And be home by a reasonable hour."
#1 offers a steadfast rule that is external to circumstance.
#2 offers a principle that is of circumstance.
Of course, this circumstance of #2 includes things that seem to exceed the now per se — previous experience, cultural norms, household norms, etc. But these are part of the circumstance, constitutive of the now.
It demands a complex negotiation of a breadth of factors. And it is by no means necessarily "more free." In fact, there are all sorts of insidious forces at work.
I mean only to point out the possibility of an emergent ethics.