Here's a situation similar to one I thought I had, but I don't, and we can't let this pondering go to waste, can we, hence blogging.
Assume the following scenario:
1. An 80B/80C appeal of the grant of a license, permit etc. There were 20 criteria for approval. The regulator found ##1-19 met, but # 20 not.
2. The applicant seeks review in Superior Court. Your client only cares about the interpretation of criterion #17. Under Rule 80B and 80C, the applicant files its brief, then "any party" can file a brief 30 days after that brief – so that's when the applicant's opponent files a brief saying the regulator was right on #20 but misinterpreted all the other criteria, and that's also when your client files a brief saying what it wants to about #17.
3. The Superior Court affirms the #20 ruling. Maybe it says nothing about criteria ##1-19, maybe it expressly upholds the regulator's factfinding on them, including #17.
4. The denied applicant then appeals to the SJC. Your client doesn't care about #20, so it doesn't file an appeal.
5. The applicant's opponent files a cross-appeal so it can argue that the regulator should also have denied on all the other criteria, including #17, based on an interpretation for #17 that you don't like. (Whether this is really a cross-appeal or just seeking to affirm a decision on alternate grounds is something I've blogged on before, but the short answer is given the current state of the law, it's at a minimum prudent to file a cross-appeal. While the cross-appellant isn't challenging the bottom line judgment – no approval – it is challenging a finding of the regulator, and under current Maine case law, that could require a cross-appeal.)
Ok, so now what? The rules (Maine Rules of Appellate Procedure 7 and 9) spell out that the applicant appellant is going to file an appellant brief. Rule 9(d) provides that if a cross-appeal is filed "the brief of the second party to appeal" files a combined Appellee/Cross-Appellant Brief. That would be the applicant's opponent, which filed the cross-appeal. That would not be your client – it didn't appeal, first or second. Rule 7(b) provides that the "appellant" can file a reply brief that responds to the Appellee brief, i.e., both supporting its appeal and responding to the cross-appeal. Similarly, Rule 9(c) references an reply "by appellant." (As I've blogged before, for some reason Maine Rule 9(d) doesn't automatically provide, as does Federal Rule of Appellate Procedure 28.1 for a reply in support of the cross-appeal – but let us not be distracted from our issue of the day).
So the appellate rules, 7 and 9, aren't like Rule 80B and 80C saying "any party" files at the appellee time. When does your client get to speak up? All it wants to do is file a response to the cross-appeal, saying the regulator's interpretation of criterion #17 was correct. It was a party, both before the regulator and the Superior Court. But it isn't an appellant before the Law Court; nor is it an appellee vis-a-vis the first appeal. It's an appellee vis-a-vis the cross-appeal.
Short answer – I would file a motion for leave to file a reply brief. Since the rules say nothing about if or when non-appellant cross-appellees can file a brief, ask to do so. When a rule is silent, it's always prudent to file a motion. It makes more sense to file at reply time, then at the "any party" Rule 80B/80C time, because you want to respond to what the cross-appellant is going to say. You are a cross-appellee, so you want to file after the cross-appellant files its brief on your issue.