Contentious (adjective)

1. Causing or likely to cause an argument; controversial.
2. Involving heated argument.
3. Tending to argue or strife.
4. Having a tendency to disagree or argue.

Origin:

From latin contentiosus ('quarrelsome').

Examples:

1. The issue of immigration is a contentious topic in politics.
2. The new policy was a contentious issue among the employees.
3. The decision was contentious and led to protests and demonstrations.