Interesting! Kavita, you have suggested very apt topics for labour day !
Priya, if you wish to venture into dangerous waters you could try the following:
1) Your current HR policies - Best Policies vs Worse Policies - Make sure to lay a rule that both sides must come out.
2) Another option is to just pick a policy such as ur appraisal policy or dress code policy and debate on that.
2) Employee knowledge on labour laws (what is legal, what is not, etc, are employees ignorant)
3) Layoffs / Recession- This will be hot !
4) If you have smokers around, then - Whether employees must be allowed to smoke during office hours or not. Even if it is a smoking chamber.
5) Who is more productive / hardworking - Female employees or Male employees - This will be fun ;)
Lastly, you could also have a simple quiz which assesses employees knowledge on employee and labour related matters and laws (notices, bonds, PF, IT deduction, etc)
Hope this helps........Have fun....
~Shikha