A "controversial topic" is something that many people have different opinions and arguments about. It is a subject that causes disagreements and conflicts among people. Full definition
My research has put me in a position to advise our clients on the complex and often controversial topic of bringing valid claims to receive information as well as to implement adequate protection mechanisms. (lawyer-monthly.com)
There are plenty of controversial topics in education policy, but perhaps none draws as much heat as the role of teachers unions. (educationnext.org)
I didn't think much about sleep before I was a mom, but it didn't take long for me to learn that this was one of the most controversial topics in parenting. (thebadassbreastfeeder.com)