Cloris Leachman today landed her 22nd career Emmy nomination for her role on Fox’s freshman comedy Raising Hope and may add to her haul of eight Emmy Awards, which is already a record for a female performer. But, despite being featured in the main credits of the show before the title card, listed as a cast member on Fox’s website and included on panels for the series, Leachman, who appeared in 20 of Raising Hope‘s 22 episodes, was nominated not as a supporting actress in a comedy series but as a guest star. The move probably helped the Oscar winner to snag a nomination in the less-crowded guest star field, but it also raises the issue of what really constitutes a guest star on a TV series as the line between a guest and supporting actor has blurred in recent Emmy races.

According to Emmy’s rulebook, “Comedy/Drama series guest performers with ‘guest star’ billing, or who are contracted as such, are eligible in the guest performer categories without regard to the number of episodes he/she appeared in.” The definition was originally limited to a single episode but was later expanded to three episodes and eventually the limit on the number of episodes was lifted altogether. Per 20th Century Fox TV, which produces Raising Hope, Leachman was technically a guest star on the first season of the show despite appearing in virtually every episode, so she was eligible for the guest starring category, something she won’t be next year as she is being promoted to a regular for Season 2.

Leachman’s guest starring nomination is part of a growing trend of the TV Academy moving away from the traditional guest starring stints involving a splashy performance in a single episode and awarding nominations for playing characters built over the course of one or more seasons that often feel like supporting roles. Not a single actor from a primetime series nominated in the guest starring categories this year has done only one episode of the show they got nominated for.

Last year, John Lithgow received treatment equal to that of Dexter star Michael C. Hall in the series’ promotional materials and was prominently featured in every single episode of the Showtime series’ fourth season. He was nominated as supporting actor at the Golden Globes and won. But at the Emmys, he was submitted as a guest star and also landed a nomination and a win. Similarly, this year Julia Stiles, who had a big presence in Dexter‘s Season 5, appearing in 10 of the 12 episodes, was nominated as a supporting actress at the Globes, but earlier today she received a guest starring Emmy nomination for the same role.

Things do seem random: Margo Martindale, nominated today as supporting actress for her role on FX’s Justified, was in 10 of the 13 episodes of the show’s second season. Her co-star Jeremy Davies was nominated as a guest star despite appearing in 11 of the 13 episodes. Cara Buono, who did 10 out of 13 episodes on Mad Men’s fourth season, also was nominated as a guest star. So was Joan Cusack, who appeared in 11 of the 12 episodes of Showtime’s Shameless. On Mad Men, John Slattery, who has appeared in a total of 49 episodes, was nominated as best supporting actor, while Robert Morse, who is credited on 40, was nominated as a guest star. Alan Cumming, who, like Leachman, got promoted as a regular on CBS’ The Good Wife this past season after starting off as a recurring guest star in Season 1, was nominated in the guest starting category last year. This year, he is nominated as a supporting actor in a drama series after appearing in 20 of the show’s 23 episodes. Glee co-star Jane Lynch received a second consecutive nomination for supporting actress in a comedy series, a category she won last year, after appearing in 17 of the dramedy’s 22 episodes from Season 2. Meanwhile, Leachman, who did 20 out of 22 episodes on Raising Hope, is considered a guest star. So is Bruce Dern, who has done a total of 29 episodes of HBO’s Big Love. And, in probably the longest guest starring run, Kathryn Joosten has landed three guest starring nominations (most recently in 2010) and two wins, all in the guest starring category, for her role on Desperate Housewives where she has appeared in a whopping 77 episodes so far.

I don’t argue that there is a need to recognize recurring guest star performances. But the guest starring categories are being used more and more for roles that feel like supporting, giving series opportunities to get more of their actors recognized and actors a choice to submit themselves as guest stars or supporting. When they opt to go as guest stars, that gives them an advantage because, as recurring, sometimes heavily, their roles are often more familiar to Academy voters than one-off guest performances no matter how strong they might be.