Mormon Consecration was and is Voluntary

In a friend's post online, a mutual friend said, "Please stop saying that the Law of Consecration was wholly voluntary." He said that you either lived the law or were excommunicated. I had never heard of anyone being excommunicated for not living consecration. So I asked for a couple of examples. He named Leman Copley.

I was not familiar with him so I read up on him "Leman Copley and the Shakers" from history.lds.org details his relation to the Shaker movement. Also from BYU Religious Studies Center,

In May 1831, the Colesville Saints, led by Newel Knight, began to arrive in the Kirtland area. Bishop Edward Partridge approached Joseph Smith and asked how to organize the group in light of the principles outlined in Doctrine and Covenants 42. In Doctrine and Covenants 51, the Lord commanded Bishop Partridge to organize the Colesville Saints “according to my laws,” appointing to each family an equal stewardship “according to his circumstances and his wants and needs” (D&C 51:3). Furthermore, the Lord explained that it was a great “privilege” to be thus organized according to the laws of the Lord (D&C 51:15).[21] Following these directions, Bishop Partridge approached a recent convert to the Church named Leman Copley. Copley was formerly a Shaker (another Christian sect involved in communal living in Ohio) and one who owned a considerable tract of farmland (759 acres in Thompson).[22] The law of consecration and stewardship was never fully practiced in Ohio. Nevertheless, at the invitation of Bishop Partridge, Copley agreed to enter into an introductory phase of the law of consecration and stewardship with the newly arrived Colesville Saints (see D&C 48:2–3). Soon thereafter, the Colesville Saints moved onto part of the Copley farm and began building cabins and working the land. 

In early June 1831, Copley broke his covenant, turned from the faith, and evicted the Colesville Saints from his land. Newell Knight traveled to Kirtland to receive directions from Joseph Smith. The Prophet inquired of the Lord. In the ensuing revelation, the Lord explained that the law of consecration and stewardship among the Colesville Saints had become “void and of none effect” (D&C 54:4). Furthermore, the Lord condemned Leman Copley for breaking his covenant (see D&C 54:5) and commended the Colesville Saints for keeping theirs (see D&C 54:6). Finally, the Colesville Saints were commanded to travel to western Missouri “unto the borders of the Lamanites” (D&C 54:8). This ended the limited practice of the law of consecration and stewardship in Ohio. It was determined that the Ohio Saints were too spread out geographically to make another attempt at that time.[23]
("Conquest of the Heart: Implementing the Law of Consecration in Missouri and Ohio", 2002, Blair G. Van Dyke )

 From The Joseph Smith Papers, it says that Leman Copley "Allowed Latter-day Saints from Colesville, Broome Co., New York, to settle on his land under law of consecration; rescinded his agreement, by June 1831." D&C 54 says the same thing.

Agreeing to live the law of Consecration is voluntary. Leman agreed to it and then he backed out of it. I do not know of other cases like this. I am guessing that they are few and far between. Being excommunicated for not agreeing to live the law of consecration let alone agreeing to it and backing out is way less common than having your wages garnished for unpaid taxes.

I would expect that there are no cases of excommunication for even backing out of consecration in the last 100 years plus.