In what country?! Sued for not telling you? For a product you don't own yet? Good luck on that!
It's because of an animal wellfare law to allows consumers to distinguish free range eggs and organic farming eggs from the industrial caged hen production.
If you don't mark your eggs (and you are not a small farm selling eggs from hand to hand which is the only exception to that law) and try to sell them you take the risk to be denounced to the DGCCRF which will apply the laws.