The case comes out of Massachusetts, where a law was enacted that allowed the personal representative of an estate to authorize access to the deceased's email account. When that was attempted in this case the email provider, Yahoo!, refused the access.
A lawsuit over the matter went to the Massachusetts Supreme Court. The family won a partial victory. The case was appealed to the U.S. Supreme Court, which declined to hear it. As a result, the decision in Massachusetts will stand.
There is still some litigation to be completed in the case, but it is an important victory for now.
An estate planning attorney can advise you in creating an estate plan that fits your unique circumstances and may include digital accounts.
Reference: Wills, Trusts & Estates Prof Blog (March 2, 2018) "Ajemian v. Yahoo! Case Update."