The NLM features an "official " canonical opinion on Summorum Pontificum in the official year book of the German Catholic Church. Gregor Kollmorgen repeated here:
The first 2008 issue of Liturgisches Jahrbuch ("Liturgical Yearbook") contains some very clear and sound notes from a canonist's perspective on the implications of Summorum Pontificum. This is all the more surprising and gratifying as Liturgisches Jahrbuch is a quarterly edited by the German Liturgical Institute (Deutsches Liturgisches Institut), the centre of German liturgical "officialdom" maintained by the German Bishops' Conference. The article (Liturgisches Jahrbuch 1/2008, p. 3 ff.) is written by Prof. Norbert Lüdecke who teaches Canon Law at the University of Bonn. A summary of the article is given in the current issue of Una Voce Korrespondenz, the quarterly of the German Una Voce association (4/2008, p. 371 ff.), of which a summary appeared, on December 1st, 2008, on the website kath-info.de, which we present to you here in an NLM translation:
1. The bishops may issue "annotations and instructions for the implementation" of the motu proprio Summorum Pontificum, but they may not add "new mandatory content" (cf. the analysis of the "guidelines" of the German Bishops' Conference by Prof. Georg Muschalek).
2. The "guidelines" of the German Bishops' Conference of 27 September 2007 are not binding upon the individual diocesan bishop.
3. The celebration of the Missa sine populo is, except in the case of insurmountable obstacles, to be allowed "at any legitimate place". "Restrictions of the usus antiquior to certain places or times by particular law are (...) inadmissible."
4. In a Missa sine populo (literally translated: "Mass without people") the faithful may participate sua sponte (i.e. without compulsion). They may also advert other faithful to this Holy Mass.
5. For a group, which according to the Motu proprio is a prerequisite for the celebration of a Holy Mass with the people, the number of three persons is sufficient. The diocesan bishop cannot establish a higher minimum number.
6. The parish priest must not discriminate against Masses according to the old use "by keeping them secret or scheduling them at times difficultly accessible".
7. "The Pope has not ordered that the parish priest could meet the request of interested faithful. He has mandated that the parish priest must do so"(Lüdecke).
8. Faithful whose right to Holy Mass in the older use is being denied by the parish priest do not only have the possibility, but the duty to inform the diocesan bishop about this.
9. "Applications" for the traditional liturgy are "not petitions of grace or favour." "Parish priests as well as diocesan bishops are legally held to meet this request" (Lüdecke).
10. The consent of the bishop to a Holy Mass according to the old use instituted by a parish priest according to the desire of faithful is not required.
11. Laypeople as extraordinary ministers of Holy Communion and women as altar servers are not allowed in the traditional liturgy.
Again, this is as excellent as it is unexpected, and its importance is not to be underestimated. The only caveat I would add refers to no. 5: I think it is an overly restrictive interpretation of Summorum Pontificum to say that a request by a group of faithful is "a prerequisite for the celebration of a Holy Mass with the people". It is a prerequisite for the faithful having a right to this Mass, not for a public celebration of the usus antiquior itself - or, as Fr Tim Finigan calls his apposite post on this question, If... but not "only if".