Canon 915: Example of Accommodation
Those upon whom the penalty of excommunication or interdict has been imposed or declared, and others who obstinately persist in manifest grave sin, are not to be admitted to holy communion. --Canon 915Cardinal Donald Wuerl of Washington, D.C., though he is to be commended for having stood with Kansas Bishop Naumann in denying Holy Communion to pro-abort HHS Secretary Kathleen Sebelius, consistently justified allowing Catholic pro-abort politician Nancy Pelosi to present herself to receive the Sacrament.
"[T]he Church just didn’t use Communion [as a] weapon," he says. "I stand with the great majority of American bishops and bishops around the world in saying this canon was never intended to be used this way."
But he wouldn't stand with the Supreme Pontiff himself, who wrote back in 2004 in the document "Worthiness to Receive Holy Communion", as then-Prefect of the CDF:
Regarding the grave sin of abortion or euthanasia, when a person’s formal cooperation becomes manifest (understood, in the case of a Catholic politician, as his consistently campaigning and voting for permissive abortion and euthanasia laws), his Pastor should meet with him, instructing him about the Church’s teaching, informing him that he is not to present himself for Holy Communion until he brings to an end the objective situation of sin, and warning him that he will otherwise be denied the Eucharist.Cardinal Wuerl is the same one who mysteriously denied permission at the last minute for a Pontifical Traditional Latin Mass to be held at the National Shrine in D.C. He is also the one who--against the clear meaning of Summorum Pontificum--required diocesan priests to first be reviewed and receive his permission before celebrating the TLM. (Compare Wuerl's icy welcome of Summorum Pontificum to the enthusiasm of Cardinal Raymond Burke, when Archbishop of St. Louis, in his letter on the subject: "[T]he extraordinary form...may be celebrated by any priest, without special permission, under the conditions set forth by the Holy Father.")
When ‘these precautionary measures have not had their effect or in which they were not possible,’ and the person in question, with obstinate persistence, still presents himself to receive the Holy Eucharist, ‘the minister of Holy Communion must refuse to distribute it’.
This decision, properly speaking, is not a sanction or a penalty. Nor is the minister of Holy Communion passing judgement on the person’s subjective guilt, but rather is reacting to the person’s public unworthiness to receive Holy Communion due to an objective situation of sin.
For a refreshing bit of muscular Christianity--in contrast to the flaccid and fearful approach of too many bishops--read Cardinal Burke's clarification on Canon 915.