Hello, and thank you very much for your questions! You've thrown quite a few of them out there, so let me try to answer them for you the best I can.
1) Can he sue her for the expense of the wedding?
He can try to sue her, but he is very unlikely to win. There are two scenarios. If a court enforces the marriage contract, he agreed in it to pay for the wedding expenses. Short of him showing that the marriage was a sham or that your sister somehow committed fraud (not the case based on the facts you have given), he would have to bear the cost of the wedding alone. If the contract is not enforced, or does not come into play, he still should not win because paying for the wedding ceremony is a gift, which is irrevocable (again, something like fraud could change things, but that doesn't apply to your sister).
2) Does she have to return the ring, other jewelry, etc.?
No, she does not. Again, there are two possible scenarios. 1) Under the contract, he agreed to give her these items. If it is enforced, she gets to keep them. 2) If the contract is not enforced or is otherwise ignored, she still gets to keep them under the law of gifts because he intended to give her the items, she accepted them, and the gift is irrevocable.
3) Can she sue him for the money in the marriage contract?
This is where it gets very interesting. There are two arguments that people have made when trying to enforce Muslim Marriage Contracts in American courts. One is that the contract is a valid prenuptial agreement. The other is that it is a regular contract between the parties.
The latter argument has been more successful than the former because valid prenuptial agreements in many states, including California, require full disclosure of assets, legal representation or a specific waiver of representation from each party, and a complete lack of coercion and overreaching from both parties. Most Muslim Marriage Contracts fail to meet at least some, if not all, of these legal tests, especially the requirement of representation or waiver. California has specifically held in at least one case that a Muslim Marriage Contract was not enforceable as a prenuptial agreement.
The other approach has been more successful, although several states have also refused to enforce Muslim Marital Contracts even as ordinary contracts. I can't find any reference to an appeals court case in California that has addressed this argument. The case I mentioned above in which the mahr was not enforced happened in a situation where the contract was viewed as a prenuptial agreement and in a context where it was the wife that sought the divorce, not the husband. Even so, the appeals court held the mahr clause unenforceable because they thought it encouraged divorce (obviously a flawed understanding).
What are you supposed to make of all of this? Well, in California, the best your sister can hope for is an uphill battle. She most certainly would need an experienced attorney to help her, and preferably she should try to find an attorney who has dealt with Muslim marriages and the issue of mahr before. Since she is not the one who sought the divorce, it is possible that she could distinguish her case from the precedent enough to get a different result. She would also want to argue that it is enforceable as a regular, secular contract as opposed to a prenuptial agreement, which an experienced attorney would be able to do on her behalf.
4) Can she sue for mental, emotional, and verbal abuse?
It is extremely difficult to win a lawsuit for mental/emotional abuse or distress in the absence of physical abuse. A suit for intentional infliction of emotional distress requires the defendant to have performed an act of "extreme and outrageous" conduct that was intended to cause and did cause severe emotional distress. Usually the distress has to be so severe that there are physical symptoms.
Extreme and outrageous conduct is "conduct which goes beyond all possible bounds of decency so as to be regarded as atrocious and utterly intolerable in a civilized community." It is more than "mere insults, indignities, threats, annoyances, petty oppressions, or other trivialities." An example of "extreme and outrageous" conduct would be something along the lines of killing someone's pet for the sole purpose of causing emotional distress to the owner.
So unless there was conduct going on that would meet the very high burden of "extreme and outrageous" conduct, your sister would not win her suit for emotional distress. However, she does appear to meet the "severe" requirement since you say she was actually hospitalized as a result of whatever was going on in the house, so she may have a real case. You should encourage her to speak to an experienced attorney about this issue as well.
Whew, that was quite a mouthful (figuratively speaking). If you need any further clarifications, please reply here and I will fill in anything that I can.
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