Prior posts of this blog have discussed that, except for certain statutory and possibly for some federal constitutional exceptions, only final judgments can be appealed in Texas practice. A real danger of summary judgment appellate practice is that a judgment, particularly a summary judgment, may appear to be final when it is not.
To explain why, let's start with a lawsuit with only one plaintiff, only one defendant and only one cause of action (As a practical point of plaintiff's trial advocacy, this normally would be a horrible idea. A wrong can normally be expressed under a number of rubrics, and a plaintiff's advocate would have a very unpleasant after-action meeting with a client in a case where the judge poured out the only cause of action where that judge might have let another cause of action to proceed to trial. If you have only one defendant, if that defendant can get dismissed, the whole case is gone. In most cases where there an individual-human-being defendant, there is also at least one other defendant, the individual-human being's employer.) Now, however, the case terminates, there is normally no doubt of what the final judgment is. If the judge rules that the case is finally dismissed, well, that's final. A summary judgment in which all relief not granted is denied is final. (This clause is called a Mother Hubbard clause--symbolically, the cupboard is left bare.) Alternatively, whatever judgment that results from a jury trial in such a case that is not subject to a new trial motion is final. Multiply the number of parties, causes of action or affirmative defenses, and you can see that partial judgments might arise that leave some parties or some causes of action or affirmative defenses undetermined. You might think that a Mother Hubbard clause would categorically solve the problem, but a judgment with a Mother Hubbard clause which clearly leaves some part of the case undecided is not final notwithstanding the clause. Yet, in a super-complicated case in which a judgment with a Mother Hubbard clause is rendered after a jury trial that the trial judge and all of the trial counsel understood to be a final judgment, that judgment might well be final notwithstanding one of a great many parties or a few of a great many causes of action clearly not being disposed of.
A fine discussion full of statutory and case cites on these points is here.
What's an appellate practitioner to do? Review the case file and account for the disposition of every party's causes of action and affirmative defenses, and move for the court to rule as to everything left unruled upon. Sometimes part of a case can be severed such that that part of the case has a final judgment that can be appealed.