I posted this question elsewhere but did not receive any reply. I repeat the question here.

I am a member of a private sport club with restricted rules. One of the rules is that a person may not be a member of this club if he is a member of another club in the area with the same objectives. To name one reason this is to have the members loyal to the club only and represent the one club only during events. There are other reasons as well. No we are in a situation where a member joined the club and we learned that he is a member at another club as well. We know we cannot force him to end his membership at the other club, but we ended his membership with us. Now he is of the opinion it is against his constitutional rights. The rule was there long before he became a member and we feel that it is our right to have this rule and therefor expel people not obeying the rule.

What is the legal situation in a case like this?