Can you say a little more about what you mean by "inclusion of lay women in church services" and "canon law to 'protect' them"? Are you talking about quasi-religious women like many anchoresses and mulieres quae beghinae vocantur?

In general, I'd say scholars mostly see the Church as responding to developments among the religiously-inclined laity (which makes a lot of sense when you realize it's a giant lumbering bureaucracy), but of course there's some push and pull, especially in terms of acceptability and--post Lateran IV (1215), the absolute need for male support with the rising centrality of the Eucharist. (Of course, this did not have to be at the level of papal dictates or legal scholasticism. In fact, that's where you see a lot of the legalistic debate being carried out--the people "on the ground" and more able to respond immediately and out of their own experience, good and/or bad and/or varied depending on the particular situation and politics.)

Elizabeth Makowski is your go-to scholar on canon law and quasi-religious women in the later Middle Ages, if that's the topic you're trying to get at. On lay women in parish life, most of the work has been done for England (the bias coming from a combo of source survival and the higher popularity of women's/gender studies in Anglophone scholarship)--I'd start with Katherine French, The Good Women of the Parish: Gender and Religion After the Black Death.

Ah, I found your other thread, too. ;) I'll try to consolidate answers with a focus on women in parish life.

A couple points of deepish background to start. First, obviously the Black Death is massive and catastrophic, and leaves a deep imprint on medieval culture. (Dancing skeletons!) But one of the things medievalists have been coming to recognize over the past 15ish years or so is that the Black Death acted more as an accelerant of trends already in progress, and that the repeated return waves were significant along with the initial calamity. Population stagnation is visibile as early as the late 13th century in Italy. So we should see it less as a radical break, and more of an intensification.

Second, religious knowledge. I was going to start with the clergy but think it probably works better to go the other way around. What did it mean to be "a Christian" in the later Middle Ages? At baptism, parents and godparents (the latter being hugely important in the MA, to the extent that godparents counted in incest calculations) would have to recite the Our Father and the Apostles' Creed. After 1215, the Fourth Lateran Council's decree that all Christians of both sexes take the Eucharist once a year, at Easter, and make a sacramental confession before it were gradually implemented across the west.

But what did this actually mean for religious knowledge? The "Christianization" of later medieval Europe is a really contentious scholarly debate, and is probably going to stay contentious given the nature of the sources. To hit on just some of the issues: First, we simply don't have immediate peasant/rural voices. Second, glimpses of lower class people acting religious in sources--for example, testifying towards a potential saint's canonization, or Joan of Arc's trial testimony--are necessarily going to be biased in favor of the the people more interested in religion and thus more likely to seek out knowledge. Third, ecclesiastical writers have a vested interest in portraying local people as ignorant and unlearned--it justifies spending more money on pastoral care for them.

I tend to come down on the side of, we see lots of piecemeal efforts at religious instruction in 13C-14C: sermons about virtues and vices, exempla (illustrative stories) meant to show how the Eucharist really is the body and blood of Christ, ritual devotions that emphasize how Christ is simultaneously divine/human. But systematic catechesis is mostly a 15C innovation.

Now, all of that has some important implications for how we treat the sources on parish priests' education/knowledge, or much more typically, lack thereof. Today, most scholars would agree the actual situation varied by individual but was not nearly as bleak as the sources tend to make it out to be (see again: vested financial interest, combined with some ugly rivalries between types of priest. Nobody in the Middle Ages hates the clergy more than other clergy). In fact, the 15C movement towards lay catechesis, given the horribly low literacy rates, was primarily achieved through better clerical education.

So what do we make of it, then, when villagers in 15C Germany complain to their bishop that their parish priest is terrible and ask for someone who can actually preach? First, obviously, it shows a level of religious awareness, knowledge, interest, and orientation already. But second, critically, it shows the desire to channel this orientation into and through the Church and the clergy.

You had asked about the flagellant movement and whether that signified a shift from a sacramental-clerical view to a devotional-lay one. In fact, over the 14-15C, there are a wild number of proliferating lay devotions, with varying degrees of leadership and approval from individual clerics and from the Church hierarchy. Even the famous late medieval heretical movements--the Hussites and the Wycliffites--seek to reform the existing Church (Luther's initial hope as well).

Some scholars see these devotions and institutions--the religious role of craft guilds; the rise of confraternities--as a blurring of lay-clergy lines; others argue that the idea of "clergy" was being redefined and circumscribed to a sacramental and maybe Latinate education role. (I'm probably more in the latter camp here. The former is attractive, but ignores just how central the Eucharist, i.e. a sacrament, was to late medieval Christian worldviews. Also confession, but that's a can of Worms. To make a horrible Reformation pun.)

Certainly the flagellants attracted a lot of opprobrium, although the reasons are more complex than "lay people getting too big for their unordained hosen." There's a strong bias towards moderation throughout the MA, possibly one of the strongest themes of pastoral care. Which, whipping yourself through the streets, not so much moderation. Another one, though--and now we're working towards French's work, I promise--involves inter-clerical rivalry.

So medieval clergy can be roughly divided into (wait for it) religious and secular. In medieval/early modern terms, this means clerics who are part of a monastic or mendicant order (typically Franciscans or Dominicans) and those who are not (secular => "in the world"). There is enormous rivalry among the two groups, and among the different orders of religious clergy. This goes all the way to the canon law level. Even those Franciscans and Dominicans are primary providers of pastoral care and preaching, especially in cities, the Church's own orientation towards public order/control/territorial power prejudices canon law towards the parish. As, frankly, does the primarily rural nature of medieval Europe, since the friars work mostly but not exclusively in towns. It's only in the mid-15C that lay people win the right to choose their confessor--until then, they're required to make their annual confession in their parish. While many civic-based, lay religious devotions like confraternities contribute to parish life, other activities like public flagellation tend to flaunt parish and even diocesan boundaries. So they're a threat to Church order and power, not just a lay/clergy boundary line.

So basically, the parish ought to be and generally was the center of lay religious life, which was increasingly important and increasingly Church-oriented over 14-15C. This is the setting for French's case about the role of women in village and town parishes in late medieval England.

She argues that women's orientation towards the Church and religious life increased over the period both as lay Christians (described above), as members of their family, and in a specifically gendered role as women. And scholars of women in this era always have to ask, did things get better or worse? French argues (like most of us do, ROFL) that in some ways these developments offered (some) women new chances for public authority even while they forced women into subordinate, gender-based roles.

Lay people, always involved in provisioning goods like candles and vestements for their parish, took on more and more of the weight of this over 14-15C (out of desire to be involved/belief that it aided their salvation, rather than an oppressive imposition), and women's participation took forms reflecting their roles in secular life. "Housekeeping and Churchkeeping" is French's expression. The favorite example here is candle-making. Candles were one of the most important provisions and donations to late medieval churches. In addition to the practical use, people donated candles to be lit for their souls or their relatives' (like when you donate the suggested 50 cents or whatever to light a candle at a touristy cathedral today for a prayer request, except taken SO SO SERIOUSLY in 15C especially). Women were the primary makers of these candles. They also took the lead in supplying altar cloths and other fabric goods, frequently making and/or decorating them themselves. French talks about women's customization of candles and textiles for different liturgical and familial uses--basically, women seizing some ownership and leaving their own mark on their parish.

Public religious life was highly gendered. Parish guilds (distinguished here from artisan ones) and confraternities were generally single-sex. Socialization was a key purpose, especially for younger men and women (the unmarried men's and women's guilds would arrange very, very specific chances for encounters between them). French argues that women's guilds restricted women's public activity to within their confines, but at the same time, allowed some women the chance to exercise a leadership role over devotional life within them. You might call this a weak version of the "power of nuns?" question.

Oh, and French closes it out by saying women had a much more positive view, in general, of themselves and their religious involvement than did the clergy. Which I'm sure comes as a massive shock. ;)

French's book is really interesting in the overall historiography because, honestly, there's not a ton in it that feels new to me about women specifically. Her broader argument, about the centrality of parish religious life, is probably the key takeaway. It's a great example of women's history done right: focusing on sources surrounding women to reshape traditional, (in this case) urban male artisan-dominated historical narratives.