Pierce Butler, Porter v. Commissioner of Internal Revenue…
“ We need not consider whether every change, however slight or trivial, would be within the meaning of the clause. Here the donor retained until his death power enough to enable him to make a complete revision of all that he had done in respect of the creation of the trusts even to the extent of taking the property from the trustees and beneficiaries named and transferring it absolutely or in trust for the benefit of others. So far as concerns the tax here involved, there is no differences in principle between a transfer subject to such changes and one that is revocable. ”
