Poisoned Chalice Meaning

(idiomatic) A scheme or instrument for causing death or harm, especially one which eventually brings about the downfall of its creator; something which is initially regarded as advantageous but which is later recognized to be disadvantageous or harmful.

Example: c. 1606, William Shakespeare, Macbeth, act 1, sc. 7:
  . . .[W]e but teach
  Bloody instructions, which, being taught, return
  To plague the inventor: this even-handed justice
  Commends the ingredients of our poison'd chalice
  To our own lips.
1818, Sir Walter Scott, The Heart of Mid-Lothian, ch. 17:
  Remember the death of Wilson was fearfully avenged; and those yet live who can compel you to drink the dregs of your poisoned chalice.
1861 May 11, W. L. Underwood, "Another Interview with Mr. Lincoln," New York Times (retrieved 25 Nov 2013):
  You need not, therefore, be surprised to hear of the vigorous blockade of the Chesapeake and Hampton Roads, and of the ports of seceded States, and that if these States erect batteries at Memphis or Vicksburgh to intercept the commerce of the Mississippi, that measures of stern retaliation or resistance will be inaugurated by the Government, to force the poisoned chalice to the lips of those who first drugged it.
1989 June 30, Antony Walker, "Iran's confident new face," The Age (Australia), page 11 (retrieved 25 Nov 2013):
  His role last year in persuading Ayatollah Khomeini to agree a Gulf War ceasefire — a decision the imam likened "to drinking from a poisoned chalice" — enhanced his reputation for pragmatism.
2013 Nov. 24, "Editorial: Reports of a Murdoch-Blair feud are good news for Labour ," The Independent (UK) (retrieved 25 Nov 2013):
  The question of whether Labour should have accepted the support of his media empire as a gift, or spurned it as a poisoned chalice, retains a certain relevance.