Should a clause state possible exceptions to make it clear they will comply with the law? For example "no animals in the building" may be seen as discrimination against people with guide dogs, so should it contain an exception and say "no animals in the building except for service animals?
Another one may be medical marijuana. If a contract states "employees may not be in possession or under the effects of drugs at work", should it add "unless prescribed by a doctor"? If they don't add this could the people who wrote the contract be sued?