A behaviour that was thought/considered (to be) acceptable in the past is not any more due to stricter/ever tightening humanitarian legislations.
Actually want to say what was acceptable in the past is not acceptable any more... Could you please rephrase the above sentence to make it look more professional please.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.
Do we need to add 'to be' between considered and acceptable ?
(Behaviour that was considered to be acceptable...)
No — it's optional.