The legal issue is what you have to show in order to get relief when the trial judge doesn't tell you -- as the statute requires -- that a guilty plea might potentially result in your deportation. It's an important issue. Even more so given that the overwhelming majority of criminal cases end with plea bargains.
The California Supreme Court decides the issue. Unanimously. In a decision by Justice Werdegar that makes total sense. As well as one that favors the defendant.
I'll nonetheless mention that I can't imagine a more sympathetic case in which the issue is raised. Here are the facts:
"[Officer] Estrada testified that on May 15, 1992, while undercover, he observed defendant Rodrigo  Martinez hand another man a brown bindle of marijuana in return for what was later determined to be $8. Defendant, an 18-year-old citizen of Mexico, was on a bicycle when the transaction occurred, and was still on the bicycle when Estrada apprehended him approximately one hour later. Defendant had no money on his person. Estrada provided a detailed description of the person he had seen, stating he had no doubt defendant was that man. Defendant was charged with a single count of the sale or transportation of
marijuana in violation of Health and Safety Code section 11360, subdivision (a).
Pursuant to the terms of a plea bargain, defendant pleaded guilty to the charged offense and received a sentence of formal probation for a period of three years, a probationary jail term of 111 days with 111 days‘ credit for time served, and was ordered to pay a fine, register as a narcotics offender, and undergo counseling. The written minute order for the plea proceeding has boxes to be checked for the advisements given a pleading defendant, including a box explaining that a defendant has been advised that the conviction might lead to immigration consequences. Unlike other boxes appearing there, the box referring to the advisement of immigration consequences is not checked. There are no other existing records of the proceedings. We accordingly presume defendant did not receive the required advisement. . . .
Defendant successfully completed probation, and nothing in the record suggests he has since had any brushes with the law. He is now in a long-term marriage to a lawful permanent resident, has four minor children who are United States citizens and, due to his wife‘s blindness, is the sole support for his family.
In May 2008, upon defendant‘s application and in accordance with section 1203.4, which authorizes relief to persons who have successfully completed probation, the superior court allowed defendant to withdraw his plea and enter a plea of not guilty, and dismissed the information against him. Defendant‘s conviction was therefore expunged from his record. That action, however, has no effect on the federal immigration consequences of his conviction. [Cite]
Two months later, defendant sought an adjustment in status to lawful permanent residency. His application was denied because of his conviction. Removal proceedings have been initiated against him, and he now faces deportation and permanent exclusion from this country."
Sometimes the particular facts of a case, though legally irrelevant to the result, nonetheless reaffirm the justice of a particular result.