If someone dies with a will, but does not mention their body or how to dispose of it, who decides what happens? Or, let's say a parent has two children and dies leaving no will; which of the siblings decides? Who pays for the result of that decision? If one sibling wants to have a huge funeral and the other wants to just toss the body in a dumpster, does the cost for the funeral come out of the estate before it is split?
Who owns a dead body?
No one, in common law countries human remains are not property and therefore have no owner.
Who is responsible for disposal?
It varies by jurisdiction.
For example, in NSW, Australia:
When the deceased has appointed an executor in their will, it is the executor’s responsibility to organise the funeral. The executor ... is not bound by specific directions left in the will.
If there isn’t a will or an executor hasn’t been appointed, the next of kin is responsible for the body. If the next of kin doesn’t want to be involved, the funeral may be arranged through the government contractor.
Where a person who dies in hospital has no next of kin or friends to arrange or pay for the funeral, and had no money or other assets, and the coroner is not involved, the hospital where they died must accept responsibility for arranging and paying for the funeral through the government contractor.
If a person died at home, and has no next of kin or friends to arrange or pay for the funeral, had no money or other assets, and the coroner is not involved, when a doctor has issued a medical certificate of cause of death, the police will complete a burial/cremation of a ‘Deceased Destitute Person’ form P372, which is sent to the Director of Public Health Unit (PHU) of the relevant Health Service. The government contractor will be contacted by the PHU to organise a funeral. If a medical certificate of cause of death was not issued, the body is taken to the coroner’s morgue.
The coroner issues an ‘Order for Disposal of a Destitute Person’ and forwards it to the Director of the relevant Health Service’s Public Health Unit (PHU). The PHU, in turn, contacts the government contractor who forwards the invoice to the PHU for payment by the Area Health Service. See the section on destitute funerals. If a Coroner’s case involves a destitute person, and there are next of kin, the counsellors at the Department of Forensic Medicine can be approached by the family to assist with funeral arrangements.
If the deceased has no next of kin, but did have money or assets, the case is referred to the NSW Trustee and Guardian who arranges and pays for a funeral from the estate.
If someone dies with a will, but does not mention their body or how to dispose of it who decides what happens?
As stated above, your requests in your will as to the disposal of your body are not binding on your executor. They must decide how to dispose of the body with consideration of their duties to the estate and beneficiaries. For example, if your will requests a funeral costing tens of thousands of dollars but your estate is worth only a few thousand then the executor is duty bound to ignore that request.
a parent has two children and dies leaving no will, which of the siblings decides?
They decide together. If they cannot agree then they will have to go to court. In general, in Australia, courts take a very pragmatic view of what should happen: quickest and lowest cost option on the table will generally win.
Who pays for the result of that decision?
The estate is responsible for funeral costs (and court costs in arguing about them). As a practical matter, funeral service providers (and lawyers) will require the person engaging their services to pay the bill; that person can then claim reimbursement as a creditor of the estate. In the event that the estate is insolvent (i.e. has more debts than assets) then their reimbursement will be less than their costs.
If one sibling wants to have a huge funeral and the other wants to just toss the body in a dumpster does the cost for the funeral come out of the estate before it is split?
Observing that to "just toss the body in a dumpster" would be illegal; the costs of the funeral come from the estate as a creditor of the estate. The residual equity of the estate would then be divided in accordance with the will or the law if there is no will.
It is worth noting that joint assets (e.g. real property owned as joint tenants, joint bank accounts) pass directly to the surviving owner and never become assets of the estate.
Laws vary by state, but usually the decedent's estate is responsible for the funeral expenses. If a loved one pays because the estate has no immediate cash, they can usually demand reimbursement from the estate later.
States also have very specific rules about who is permitted to claim a body and make funeral arrangements and what to do in the rare case where there is a conflict. See, e.g., http://www.kslegislature.org/li/b2015_16/statute/065_000_0000_chapter/065_017_0000_article/065_017_0034_section/065_017_0034_k/
The following persons, in order of priority stated, may order any lawful manner of final disposition of a decedent's remains including burial, cremation, entombment or anatomical donation...
Usually, a will cannot be probated in time to address disposal of the body and the decision is usually left to next of kin.
More often than not, the person who takes initiative and gains practical control of the body first ends up deciding.
It is very rare that the matter ultimately gets decided by a court, and while some jurisdictions, such as Kansas, have detailed provisions governing who gets to decide, others do not and leave the matter in the general discretion of a judge in the event that there is a dispute, potentially greatly delaying disposition of the body.
Usually disputes arise in cases of "blended families" or when one member of the family wants a burial in a military cemetery and another relative doesn't.
Funeral expenses are usually reimbursable by the estate. Also, while this by all rights should be patently illegal, I have observed funeral homes accepting credit card payments on the deceased individual's credit card to pay for a funeral on multiple occasions that are processed by the credit card company and accepted as valid without objection.