The left side of the shield in the center is the coat of arms of the Archdiocese of Seattle. It is a composition of two emblazonments: the family coat of George Washington, a reference to the state of Washington, and the archdiocesan coat. The Washington family coat was a white field with two red bars and three mullets (five-pointed stars) in chief also in red. The archdiocesan coat is superimposed on the Washington coat, the crosses replacing the stars. The pyramid symbolizes the towering form of Mount Rainier.
For his personal arms, the right side of the shield in the center, Archbishop Murphy has drawn on a series of double significances to reflect the meaning of his baptismal name, "Thomas," which is taken from the Aramaic meaning "twin." This is seen in the use of two heraldic ordinaries, quartering, which is the division of the shield into four parts and the fess, which is a broad black bar running from side to side across the middle of the shield. These two ordinaries, as well as the two dominant colors, red and silver, are taken from the coat of arms of the Irish family surname O'Murphy.
In each of the red quarters is a silver lion rampant from the O'Murphy coat of arms. There are two of these reflecting not only the family surname and Irish heritage of the archbishop's father, Bartholomew Murphy, but also his mother Nellie's maiden name, which was also Murphy.
Blue chevrons in the silver quarters are from the coat of arms of St. Thomas More and double in meaning by representing the carpenter's square of Archbishop Murphy's second patron, St. Thomas the Apostle. The chevrons are blue, the color of Mary, to honor the patroness of St. Mary of the Lake Seminary where the archbishop served as Rector from 1973 to 1978. The color blue doubles in meaning for the waters of Lake Michigan upon which the city of Chicago sits. Archbishop Murphy was raised in Chicago and served as a priest there from 1958 until his elevation to the episcopacy in 1978.
The second heraldic ordinary, the fess and its charges, the garbs of wheat, are also taken from the O'Murphy family coat of arms. The fess is black to symbolize Archbishop Murphy's vocation in life through the use of the priestly color. The twin garbs are for the Holy Eucharist to which Archbishop Murphy dedicated his life as a priest and for the Archdiocese of Seattle for whose people the archbishop dedicated his life in service of their needs.
For his motto, Archbishop Murphy selected "In Christ Joy and Hope." The first phrase "In Christ" derives from "All Things Come Together in Christ" - the episcopal motto of Pope Saint Pius X, who established the Diocese of Great Falls, MT in 1904. Archbishop Murphy served as the fifth bishop of this diocese from 1978 to 1987. The second phrase "Joy and Hope" comes from the Second Vatican Council's document "The Church in the Modern World" which completes the "twin" significance of his coat of arms, reflecting the archbishop's ministry in the modern world and his foundations in the heritage of Holy Mother, The Church.
The achievement is completed with the external ornamentation of the gold metropolitan cross, placed in back of the shield and extending above and below, and the pontifical hat which was worn at solemn conclaves before 1870, with its ten tassels in four rows on either side of the shield, all in green. These are the heraldic insignia of a prelate of the rank of archbishop.