Answered by Barbara Bair:
Garvey's conviction on a charge of mail fraud was basically a technicality. As Garvey put it in a speech at Liberty Hall in New York on 20 May 1923, the mail fraud case against him "involves not Marcus Garvey but the existence of the Universal Negro Improvement Association (U.N.I.A.). The ideals of the Universal Negro Improvement Association are on trial."
Before settling on a mail fraud charge, government officials who were looking for an angle to use to challenge the UNIA on a legal basis had explored other possible avenues for prosecuting Garvey, including income tax evasion. The mail fraud charge they actually settled on stemmed from the purchase of Black Star Line stock through the U.S. mail in response to the advertisement in UNIA brochures and in the pages of the _Negro World_ newspaper of a new ship which had been dubbed the S. S. Phyllis Wheatley.
While these ads included photographs of the ship and promises of its impending launching and travel to Africa, the Black Star Line, Inc., had not actually completed negotiations for the purchase of the ship at the time the advertisements were run, and indeed, was having great difficulty guaranteeing payment. It was a Catch-22 situation for the UNIA--the sale of stock was needed to raise the funds necessary to fully complete the transaction that would legally transfer the ownership and operation of the ship to the Black Star Line, but at the same time, the UNIA did not officially own the ship in question for which it was issuing stock.
The UNIA constantly faced a conundrum regarding under-capitalization. Steeped in bills from the mechanical failures of previous ships, unable to meet payroll demands of crews, and facing other financial problems, the UNIA and ACL still needed to maintain the public profile that the Black Star Line afforded. Whatever its problems in actually functioning, the Black Star Line was a powerful symbol of black enterprise. It represented the ideal of unity between peoples of the African Diaspora, and the goal of linking together America, Africa and the Caribbean in both symbol and in fact. For many, it represented the hope of repatriation, or the "Back to Africa" promise that was an important inspiration to many UNIA members. It was also about leadership, and reversing long maintained patterns of racial power and labor. UNIA leaders hoped to create a black-owned shipping industry where, as Garvey put it, black men would be at the helm instead of in the hold of the ship, as well as a working passenger line in which black travelers would be treated with dignity, and an international shipping system whereby mineral resources and agricultural and industrial products could be exchanged between black producers and consumers, circumventing the white economy. The Black Star Line ships also were important organizing tools, galvanizing the imaginations of fledgling Garveyites in the ports they visited. UNIA organizers traveled aboard the ships. They promoted shipping line stock, supported existing UNIA divisions, and helped found new ones.
Sale of shipping stock was also crucial to the ongoing financial health of the organization at large. For all these reasons, financial, political, economic, and symbolic, Garvey and the UNIA sought to maintain their efforts in shipping, despite the focus of his mail fraud case on the financial management (or alleged misrepresentation of the facts of purchase and ownership) of the organization's shipping line. In choosing to pinpoint the sale of Black Star Line stock as the matter before the courts, government officials were indeed, as Garvey said, attacking not only him as an individual, but the ideals of the UNIA. It should be remembered, however, that many black leaders as well as white government officials were concerned about the level of mismanagement and alleged corruption and misreporting of funds involved in the day to day operation of the UNIA's shipping lines, and the impact on poor people whose meager funds went to the purchase of Black Star Line stock.
The mail fraud case thus centered on much more wider political issues than the narrow charges actually leveled at Garvey--charges which actually came down to the sale of stock to one individual, named Benny Dancy, out of the thousands who purchased stock in the early 1920s.