The burden split is the structural fact, and it is more even-handed than it looks. The proponent of the will has to make out prima facie proof of due execution in every case, whether contested or not, which is why a self-proving affidavit signed at the same time as the will is worth having: it lets the will be proved without tracking down the witnesses years later. Where the proponent is also the person petitioning, they additionally carry prima facie proof of death and venue. A petitioner seeking to establish intestacy instead carries prima facie proof of death, venue and heirship. Only after those threshold showings does the contestant's burden arise, and it runs to the specific ground alleged. Minnesota adds that "parties have the ultimate burden of persuasion as to matters with respect to which they have the initial burden of proof," so nothing shifts back.
Standing is defined more loosely than in ordinary litigation, and deliberately so. Minnesota's definitions section describes an "interested person" as one that "includes heirs, devisees, children, spouses, creditors, beneficiaries and any others having a property right in or claim against the estate of a decedent, ward or protected person which may be affected by the proceeding," together with persons having priority for appointment as personal representative and fiduciaries representing interested persons. Then it adds a sentence worth reading twice: "The meaning as it relates to particular persons may vary from time to time and must be determined according to the particular purposes of, and matter involved in, any proceeding." So the category is functional rather than fixed, and the practical test is whether the outcome would change what this person receives. A child written out of a will is an interested person because they would take by intestacy if it fell. A friend who was left nothing and would take nothing either way generally is not.
The deadline is the thing that ends most contests before they begin. Minnesota's section 524.3-108 bars almost every probate, testacy or appointment proceeding commenced "more than three years after the decedent's death," and then carves out three exceptions. The third is the contest window: a proceeding to contest an informally probated will, and to secure appointment of the person with legal priority if the contest succeeds, "may be commenced within the later of 12 months from the informal probate or three years from the decedent's death." That is a genuinely short period measured against how long it usually takes a family to discover there is a problem, and it runs independently of whether the estate has been distributed.
The consequence of winning is the part contestants most often have not thought through. Setting a will aside does not give the court a free hand to do what seems fair. It removes one document, and something else then governs: an earlier valid will if there is one, and otherwise the state's intestacy statute, which distributes to relatives in a fixed statutory order. Either outcome can be worse for the contestant than the will they attacked. A person left a modest bequest by a will and nothing at all by the intestacy schedule has, in winning, taken their own share to zero. That calculation belongs at the beginning, and it is separate from the question of whether the will can be beaten.
Two related mechanics sit either side of this page. A no-contest clause changes the price of filing rather than the merits, and it reaches only someone the will actually left something. And a will offered against a later will has its own ordering rule: Minnesota provides that where a will is opposed by a petition to probate a later will revoking it, the court determines first whether the later will is entitled to probate, since the answer to that question may dispose of everything else.