There are many good reasons to put in place a sound estate plan. Certainty about the transmission of property to the desired beneficiaries in a timely manner is primary. Estate tax considerations and other factors also often play a role.

In other words, people in the Boston area and across the nation have many positive incentives to make sure wills, trusts and other estate plan documents are in good shape.

But considering the burdens that an estate battle can involve, there is also a negative incentive to get your estate plan ducks in a row. After all, no well-intentioned testator wants to have the distribution of his or her estate held up by protracted challenges.

Yet that is what has happened in a current case in which estate litigation has been going on for two decades. The case involves the heiress to a copper-mining fortune who left behind two conflicting wills.

In the first will, the bulk of the woman’s fortune went to distant relatives. In the second, the distant relatives were given nothing. But her caretaker received much more substantial sums than in the first will. The second will, executed only one month after the first, also designated several charities for large gifts.

Among the assets at stake is an acknowledged masterwork of painting, one of the Water Lilies series by Claude Monet.

The case is of interest, however, not merely for the presence of a famous painting or for the large amount of money involved. The case is relevant across a range of income levels because it raises clearly the question of capacity to make a valid will.

The woman who executed the two wills was 98 when she did so. Obviously that is an age at which mental faculties may be badly eroded. But at what point does someone become no longer able to take care of their own financial affairs?

Source: New York Times, “How to Avoid an Estate Battle After You Die,” Paul Sullivan, June 14, 2013