In the case of M.P.M. Builders, LLC v. Dwyer, 442 Mass. 87 (2004), the Massachusetts Supreme Judicial Court adopted the American Law Institute's "modern rule" on the relocation of easements in the Restatement (Third) of Property (Servitudes) Section 4.8(3) (2000). The owner of property subject to an easement can relocate the location of the easement without the consent of the easement holder, subject to certain conditions.
The law Massachusetts is the minority position. The majority of states require mutual consent to change the location of an easement.
Section 4.8(3) provides that:
Unless expressly denied by the terms of an easement, the owner of the servient
estate is entitled to make reasonable changes to the location or dimension of an
easement, at the servient owner's expense, to permit normal use or development
of the servient estate, but only if the changes do not (a) significantly lessen
the utility of the easement, (b) increase the burden on the owner of the
easement in its use and enjoyment, or (c) frustrate the purpose for which the
easement was created.
If you are getting the benefit of a new easement in Massachusetts, you should make sure that the easement may only be relocated with mutual consent of the parties. This will allow you to control the relocation and frustrate the relocation if necessary. If you are getting the benefit of the easement, you probably do not want to have that language, so you some possibility of relocated the easement for future development of your property.
The Land Court case of Moses et al v. Cohen et al. (Mass. Land Ct. Jan. 12, 2007) highlighted the ability of the easement holder to block relocation by inserting language into the easement that requires the holder's consent for relocation. It also pointed out that you should clarify the purposes of the easement so that those purposes can be considered in deciding of the relocation is appropriate. For example, if the easement is not just for access, but to preserve a view or prevent erosion.
There is a great article on the topic in the Massachusetts Bar Association Section Review publication by E. Christopher Kehoe and Timothy C. Twardowski of Robinson & Cole LLP