FairMormon is a non-profit organization dedicated to providing well-documented answers to criticisms of LDS doctrine, belief and practice.
Pergunta: Qual é a "Lei de Adoção" praticado entre mórmons e 19 do século por que ele mudou?
Question: What is the "Law of Adoption" practiced among 19-century Mormons and why has it changed?
Since few of the Church members had ancestors within the young Church, they often chose to seal themselves to prominent Church leaders such as Joseph Smith or Brigham Young
Joseph Smith was very anxious to have the Saints sealed—since few of the Church members had ancestors within the young Church, they often chose to seal themselves to prominent Church leaders such as Joseph Smith or Brigham Young. The key understanding was that an unbroken chain of sealing was required, to bind the whole world into a single human family.
President Wilford Woodruff explained how he and other Church presidents had felt about the matter:
I have not felt satisfied, neither did President Taylor, neither has any man since the Prophet Joseph who has attended to the ordinance of adoption in the temples of our God. We have felt that there was more to be revealed upon the subject than we had received. Revelations were given to us in the St. George Temple, which President Young presented to the Church of God. Changes were made there, and we still have more changes to make, in order to satisfy our Heavenly Father, satisfy our dead and ourselves. I will tell you what some of them are. I have prayed over this matter, and my brethren have. We have felt as President Taylor said, that we have got to have more revelation concerning sealing under the law of adoption."
President Woodruff then announced to the General Conference and particularly to the presidents of the four temples in Utah that he had gone "before the Lord" to know who he should be adopted to and that the "Spirit of God" instructed him that he should be sealed to his natural father. Prior to this time it had been the practice to be sealed to the "prophets and apostles" in the Church. President Woodruff now pronounced the prior practice an incorrect procedure and called upon the membership of the church to accept as a revelation this announcement, which incidentally he had previously presented to his counselors and to the Quorum of Twelve Apostles. 
The Church believes in modern prophets, which would be a superfluous fixture of the Church were it not for the belief in on-going revelation:
For behold, thus saith the Lord God: I will give unto the children of men line upon line, precept upon precept, here a little and there a little; and blessed are those who hearken unto my precepts, and lend an ear unto my counsel, for they shall learn wisdom; for unto him that receiveth I will give more; and from them that shall say, We have enough, from them shall be taken away even that which they have.(2 Nephi 28:30)
The Church is a revealed religion that believes in on-going revelation
Critics—often coming from a fundamentalist perspective—assume that nothing should change in the Church. But, the Church is a revealed religion that believes in on-going revelation. The Saints consider change in practice and expansion of doctrinal understanding to be a strength, not a weakness. Those who want no change in their religious practice or understanding will likely be disappointed in the Church of Jesus Christ.
There may also have been some important reasons for understanding the Law of Adoption differently in previous times. The Saints' understanding of adoption in Brigham Young's day contributed to the solidarity and interdependence that helped them cross the plains to Utah—the Saints' understanding of the "law of adoption" as a social order helped them to survive.  When circumstances allowed them to expand their understanding, this was revealed to the prophet.
The Saints' understanding of the Law of Adoption has grown and expanded. They are not ashamed to say that they now understand more clearly. Indeed, they insist upon such a perspective and rejoice in it. The Saints also continue to believe that the Lord " will yet reveal many great and important things pertaining to the Kingdom of God." Articles of Faith 1:9
This is not a change in LDS belief: the Church still believes that all mankind must be sealed into an unbroken chain, a great eternal family. But, the Church understands more clearly how the Lord wishes this to be accomplished—via proxy sealing of children to parents as far as is possible. Sealing beyond that will await the Millennial years of the Lord.
If prophets cannot expand our understanding of key matters such as this, and modify them as circumstances require, what use are they? Critics should cease trying to impose their inerrantist expectations on the Church.
- Messages of the First Presidency, edited by James R. Clark, Vol. 3, (Salt Lake City: Bookcraft, 1966), 251 (emphasis added). GospeLink (requires subscrip.) GL direct link
- Richard E. Bennett, We'll Find the Place: The Mormon Exodus 1846–1848 (Salt Lake City, Utah: Deseret Book, 1997), 77–83. ISBN 1573452866. GL direct link