Not only does the case carry his name, but there is also the "Lemon Test," the three-prong standard judges use to analyze if a policy or law violates the First Amendment's required separation of church and state.
Lemon's journey into legal history is not the civics-class cliche: a lone crusader "fighting all the way to the Supreme Court."
His - like many famous cases - was serendipity.
Born in Atlanta and raised a Baptist, Lemon came to Philadelphia in the 1950s after a tour in the Army and marriage. Lemon's travels coincided with a spiritual journey to what he calls "ethical humanism" - reliance on reason in conducting human affairs.
It was in the Army, Lemon said, that he first began thinking about the First Amendment's so-called establishment clause: "Congress shall make no law respecting an establishment of religion."
In Philadelphia, Lemon said, he followed his interests and began attending the American Civil Liberties Union's monthly meetings.
At the same time, Pennsylvania's legislators were dealing with a financial crisis in the Catholic schools.
The legislature's solution, enacted in 1968, was Act 109, the first state law in the nation providing public tax funds to religious schools. Pennsylvania would reimburse private schools for teaching four secular subjects: math, modern foreign languages, elementary science, and physical education.
In return, private schools had to use certain accounting methods to ensure that taxpayers did not fund religious instruction.
It was a watershed for the establishment clause. Rhode Island soon enacted a similar law.
Lemon recalled that he was attending an ACLU meeting in Philadelphia when the executive director broached the idea of suing over Act 109.
Under provisions for constitutional challenges, the suit was heard by a special three-judge federal panel with immediate Supreme Court review.
The special panel rejected the ACLU challenge, 2-1, saying the First Amendment does not "require an absolute separation between necessarily overlapping interests in the secular education of school-age children."
On June 28, 1971, the Supreme Court reversed the decision, unanimously invalidating the two states' laws, which had been combined on appeal.
"We are confronted with successive and very likely permanent annual appropriations that benefit relatively few religious groups," wrote Chief Justice Warren Burger.
With churches vying with other groups for state money, "divisiveness on religious lines [is] thus likely to be intensified," he wrote.
Moreover, Burger wrote, acceptance of public money would curtail religious freedom: "Government grants . . . have almost always been accompanied by varying measures of control and surveillance."
The decision touched off the predictable political firestorm. Cardinal John Krol, then head of Philadelphia's Roman Catholic Archdiocese, called opponents of the state law "emotional bigots," "nativists and Ku Kluxers."
Lemon said the furor did not touch him or his family. Lemon's wife, Augusta, was a nurse in both public and parochial schools, and their son, Anthony, then 12, was a pupil at the local Charles W. Henry School.
There are no visible mementos of Lemon v. Kurtzman in Lemon's living room, which is crowded with plants, books about jazz and the black experience, and a sketch of the late Rev. Dr. Martin Luther King Jr.
Lemon met King and his family when they attended Morehouse College, from which Lemon earned a math degree.
Lemon attended the Supreme Court arguments in the case. What sticks in his mind was the brilliance of his attorney, Henry W. Sawyer 3d, the legendary Philadelphia civil-rights lawyer.
"When your case gets to the Supreme Court," Lemon added, "it's a lawyer's day in court. It doesn't matter to the justices if you are dead or alive."
How long Lemon v. Kurtzman will stand is almost a betting matter among lawyers.
Five of the nine sitting Supreme Court justices have, sometimes harshly, criticized the Lemon Test. Yet, as recently as 2001, the court chose not to review a case presenting an opportunity to reverse Lemon.
Locally, the test was used last year by U.S. District Judge Stewart Dalzell in ordering that a 1920 plaque containing text and commentary on the Ten Commandments be removed from a West Chester courthouse wall.
Chester County officials have appealed the case to the U.S. Court of Appeals for the Third Circuit, and it may become the next Supreme Court challenge to Alton Lemon's legacy.
On March 4, 2002, as Dalzell was hearing heated testimony in the Ten Commandments case, Lemon sat unrecognized in the rear of the packed courtroom, listening to the debate and the disparaging of the legal test bearing his name.
At a break, someone cued Dalzell, who introduced the somewhat embarrassed Lemon to the audience.
Today, Lemon smiles at the memory but is more subdued considering the future of the First Amendment.
"I'm not surprised," Lemon said, "but separation of church and state is gradually losing ground, I regret to say."
Contact staff writer Joseph A. Slobodzian at 215-854-2658 or firstname.lastname@example.org.
The "Lemon Test"
The First Amendment's "establishment" clause speaks to the separation of church and state. With the Lemon case, the Supreme Court began using three criteria to assure a law or policy is not in violation:
"First, the statute must have a secular legislative purpose;
"Second, its principal or primary effect must be one that neither advances nor inhibits religion;
"Finally, the statute must not foster 'an excessive government entanglement with religion.' "
- Chief Justice Warren E. Burger, Lemon v. Kurtzman, 1971.