Texas held its 2010 primary on March 2, and the Democratic Party did not have any candidates for Judge in the 432nd district in Fort Worth. The Republican primary nominated Tom Zachry for that post. However, Zachry died on March 19, 2010.
Texas election laws let the Republican Party replace Zachry with a new nominee, but the law does not let any other qualified party make a late nomination in circumstances like that. On August 17, the Texas Democratic Party filed a lawsuit with the Texas Supreme Court, asking the Court to construe Texas election law to let it make a nomination as well. In re Candace Taylor, 10-0635.
In 1916, the Texas Supreme Court ruled against the Democratic Party is a case somewhat like this one. That case was Gilmore v Waples, 188 S.W. 1037.
It is inevitable that some primary winners will die after the primary, but before the general election. However, this problem is made worse when states have primaries that are as early as March, a full eight months before the general election. The problem is even worse in Texas, which requires all candidates (except presidential candidates) to file a declaration of candidacy in early January of any election year.