Texas’s highest noncivil tribunal unanimously decided that the ban on political contributions was constitutional. Defendants James W. Ellis and John D. Colyandro challenged the money-laundering statute— that it doesn’t apply to checks— by a pretrial writ of habeas corpus. The CCA held that the challenge to the latter statute was premature.
When the Supreme Court of the United States considers whether campaign contributions and independent expenditures on behalf of a candidate are constitutional to regulate, it treats them differently. That court is willing to regulate the contributions but not those independent expenditures. The first is a regulation of the way money can be given to candidates; the latter is held to be regulation of political speech, the main thing that the first amendment's speech protection is supposed to protect. In Citizens United v. Federal Election Commission, the court held that the government may regulate corporate political speech through disclaimer and disclosure requirements, but it may not suppress that speech altogether.
SCOTUS said that corporations are entitled to first amendment protection because they are simply "associations of individuals." If one cannot limit an individual's independent expenditure, then one cannot limit expenditures made by associations of individuals. However, if one can limit an individual's contributions, as in Buckley v. Valeo, then laws can be enacted to prevent associations of individuals from being used to circumvent those contribution limits, like Texas's law. Moreover, corporations in Texas have many ways to engage in political speech: it's not like they're gagged. Citizens United is not implicated by Texas's regulations of the forms for corporations' contributions.
Generally,pretrial habeas cannot be used to attack a charging instrument's sufficiency nor can it be used to construe the meaning and application of the statute defining the offense. It can be used to advance a claim that a statute is unconstitutional on its face, but not that a statute is unconstitutional only because of how it is applied. This is because only a trial can show the facts of how the statute is applied. It's too early.