。
It's everyone's duty to obey the law.
Literal
Law [dat-に] obey [nominalizer-の] [topic-は] everyone [possessive-の] duty-[assertion-だ]
我々 → みんな is a register shift worth noticing. みんな ('everyone') is more conversational; 我々 is more formal and institutional. Same proposition, different audience — みんな fits a casual setting where 我々 would feel stiff.