Complex sentence: In 2017, the eligibility of Australian parliamentarians with actual or possible dual citizenship to sit in the Parliament of Australia was called into question, amounting to an ongoing political event referred to variously as a constitutional crisis or the citizenship crisis.
Split into simpler sentences: In 2017, the eligibility of certain Australian parliamentarians to sit in the Parliament of Australia was called into question because of their actual or possible dual citizenship. This became an ongoing political event referred to variously as a constitutional crisis or the citizenship crisis.