An appellee who seeks to enlarge its own rights under the judgment must cross-appeal. One who merely wishes to defend the judgment need not.
The rule. An appellee may urge any ground appearing in the record in support of the judgment, including grounds the trial court rejected, without cross-appealing. To obtain more than the judgment gave — additional damages, a broader injunction, relief on a dismissed claim — a cross-appeal is required.
Conditional cross-appeals are common: a party satisfied with the judgment but wishing to revive an alternative claim if the judgment is reversed. These should be labelled as conditional so the court understands the sequence.
Briefing consequences. Cross-appeals alter the briefing order and lengths, and give the cross-appellant an additional brief. That structural advantage is sometimes the reason a marginal cross-appeal is filed, and courts notice.
Strategic cost. A cross-appeal signals dissatisfaction with the judgment and invites the panel to reopen matters the appellee has already won. It also enlarges the record and the argument time devoted to issues other than the principal one.
Deadlines. The cross-appeal period is typically measured from the filing of the first notice of appeal and is short. Missing it forfeits the enlargement, not the defence.