From Neil Foley, “Partly Colored or Other White: Mexican Americans and Their Problem with the Color Line,” in Beyond Black and White. 127, 142
Although many Mexicans had lived in Texas long before Stephen Austin established the first Anglo settlement in 1822, Anglos still regarded Mexicans as alien culturally, linguistically, religiously, and racially. Their status as racially in-between, as partly colored, hybrid people of mixed Indian, Spanish, and African ancestry, made them suspect in the eyes of whites, who feared that Mexicans could breach the color line by marrying both blacks and whites. Although laws existed against race mixing for whites and blacks, no such laws prevented the mixing of Mexicans with both blacks and whites.5
5. Peggy Pascoe, “Miscegenation Law, Court Cases, and Ideologies of ‘Race’ in Twentieth-Century America,” Journal of American History 83 (June, 1996): 44-69. Mexicans, who were legally “white,”were rarely prosecuted for marrying blacks. For the only case in Texas of a Mexican brought to trial for marrying a black, see F. Flores v. The State, 60 Tex. Crim. 25 (1910); 129 S. W. 1111. I am indebted to Julie Dowling for bringing this case to my attention. See her paper, “Mexican Americans and the Modern Performance of Whiteness: LULAC and the Construction of the White Mexican,” presented at the American Sociological Association annual conference, Anaheim, Calif., August, 2001.
From F. Flores v. The State (1910), in The Texas Criminal Reports Volume 60.
The evidence shows that appellant was a Mexican, or of Spanish extraction. There is no evidence in the record that he had any negro blood in his veins, and his testimony, as far as it goes, excludes the idea that such was the case. The testimony of the woman appellant married, Ellen Dukes, goes to show that she had negro blood in her veins, but within what degree is not shown. She is variously described by the witnesses, and some of them go sufficiently far to say that she looks like a negro. These witnesses state that her physical makeup, and especially the fact that her face and hair, indicate that she was a negro. She testified that she was born and raised in San Antonio and was 31 years of age; that her mother’s name was Refugio Gonzales; that her father’s name was Garmo Dukes; that her mother was Mexican while her father had some negro blood, but she did not know how much negro blood or how much Mexican blood; but that he did have some negro blood in him; that her father’s color was very bright, a great deal brighter in color than herself; that his hair was not kinky or nappy like the ordinary negro–not as much so as was her hair–that it was straighter. Those witnesses who testified to the fact that the woman appellant married was of negro extraction were not aware of how near she was to purity of negro blood; they did not know whether she was within the specified degrees mentioned in article 347 of the Penal Code or not.
From Charles Frank Robinson II, Dangerous Liasons: Sex and Love in the Segregated South
 Other interracial couples remained relatively inconspicuous by hiding under the cover of color closeness. Individuals who could cloak their African ancestry could often marry across the color line without alerting state authorities. Even if the state discovered that one of the parties in the relationship had some racial mixture, the state would then have the very difficult task of proving that the individual in question had sufficient black ancestry. Such was the case in Flores v. State (1910). On June 9, 1909, F. Flores and Ellen Dukes married in Angelina County, Texas. Within months after their ceremony, state authorities arrested the couple and charged them with violating the state’s anti-miscegenation law. The state contended that Flores was of Mexican descent, thereby making him  a white person for purpose of the statute. Yet Dukes had both Mexican and African origins. In the Angelina County district court trial, Dukes never denied having African ancestry. However, she testified that she did not know how much African ancestry she possessed. According to Dukes, “her mother was Mexican while her father [Garmo Dukes] had some negro blood.”
The state presented Ellen Dukes’s physical appearance as evidence of her guilt. She apparently had rather dark skin and somehwat “kinky hair.” The state also produced witnesses who gave testimony that they believed Dukes to be “a Negro.” These same witnesses further told of conversations that they had had with Flores in which he confirmed to them that he was “a Mexican and had no Negro blood in him.”
The state convicted Flores and Dukes. The couple appealed to the Texas Court of Criminal Appeals. Although the court acknowledged that Dukes had black blood, the court held that the state had failed to prove the degree of it. Dukes did not know when questioned. Neither did any of the state witnesses. According to the high court, the Texas anti-miscegenation law obligated the state to show “that one of the parties had sufficient blood to prohibit the marriage.” Since there was a “reasonable doubt” about Dukes’s percentage of African mixture, the court reversed the lower court verdict.
 The case of Marre v. Marre (1914) was another instance when color closeness protected the marital interests of a person involved in an interracial relationship. In 1911, Louis Marre sued for an annulment of his three-year marriage to Agnes E. Nash Marre. Louis claimed not only that he had married Agnes under “duress” but that Agnes was a person of color. A St. Louis Circuit Court found in Louis’s favor, and Agnes appealed. Upon reviewing the case, the Missouri high court could find  nothing to substantiate Louis’s claims. The court saw no duress. Although Agnes’s sixty-year-old mother had insisted that Louis marry her daughter, who was pregnant at the time, and allegedly threatened him with bodily harm if he failed to do so, the court did not consider this duress. According to the court, “Mere apprehension of physical or possible physical injury, is not sufficient” to constitute duress.
With regard to the charge of Agnes’s African ancestry, the Missouri Supreme court did not believe that the evidence substantiated the conviction. Agnes and her mother unequivocally denied having any black heritage. They acknowledged that they had a few black friends but argued that their apparently tanned appearance was a result of the Mexican origin of one of their immediate ancestors. Agnes also used the fact of her two sisters having married white men as further evidence of her legal whiteness.