Grammy officials will tell you that Best New Artist is the hardest category to get right. In years past, sometimes they've been too lenient about eligibility (Shelby Lynne was on her sixth studio album when she won). Other times, they've been too strict (Richard Marx was knocked out of contention for having had one song on the Nothing in Common soundtrack—an album that wasn't even a hit).

Here are some of the artists whose eligibility this year was in question for one reason or another, together with how the Recording Academy, with the help of a large screening committee, decided these cases.

First, some "borderline cases" that made it onto the list of 374 eligible artists.

Eligible

Alessia Cara. The singer/songwriter was allowed in even though her 2015 hit "Here" was a smash. It was certified double platinum by the RIAA on Jan. 7, 2016—nearly nine months before the start of the current eligibility year (Oct. 1, 2016-Sept. 30, 2017). Cara also had another platinum single ("Wild Things") and a gold album (Know-It-All) prior to the start of this eligibility year—a year in which she built on that early success with numerous hits.

Lil Uzi Vert. The rapper was allowed in for his first full-length album, Luv Is Rage 2, even though he had released four mixtapes, including the hits Lil Uzi Vert vs. the World and The Perfect Luv Tape, prior to the start of this eligibility year.

Logic. The rapper was allowed in for his third album, Everybody. His first two albums, Under Pressure and The Incredible True Story, were both hits, though they weren't certified gold until this year. Logic also had five earlier mixtapes, including the hit Bobby Tarantino.

Jon Pardi. The country singer is on his second album, California Sunrise. He is nominated for New Artist of the Year at the CMA Awards.

Old Dominion, The country group is also on its second album, Happy Endings. The group is also nominated for New Artist of the Year at the CMAs.

AJR. The indie pop band is eligible for its second album, The Click.

Noah Cyrus. Artists no longer have to have released an album to qualify. Cyrus' long-delayed debut album, NC-17, has yet to be released, but she has released five or more tracks and thus qualifies.

Hailee Steinfeld. The actress/singer has yet to release her first full-length album, but she released an EP, Haiz, in November 2015.

Jordan Smith. Smith, who won The Voice in December 2015, released his debut album, Something Beautiful, in March 2016. The Grammys decided he should get another shot.

And now, some "borderline cases" that didn't make it.

Not Eligible

Migos. The hip-hop trio wasn't allowed for its sophomore album, Culture. The trio had released 15 mixtapes prior to the start of this eligibility year. (The new rules say an artist "must have released a minimum of five singles/tracks or one album," but cannot have released "more than 30 singles/tracks or three albums" prior to the start of the current eligibility year.)

Rag'n'Bone Man. The highly-touted English singer/songwriter isn't on the list for his first album, Human.

Lauren Alaina. The country singer is up for a CMA award as New Artist of the Year. She may have been knocked on the grounds that she attained prominence in 2011 when she was runner-up to Scotty McCreery on Season 10 of American Idol.

Harry Styles, Niall Horan, Liam Payne. The One Direction alums all had big hits during the year. 1D was never nominated for a Grammy (!), so these alums could conceivably have been eligible here as solo artists, but the committee (wisely) decided that their 1D success gave them prominence.

A Boogie Wit da Hoodie. The rapper isn't on the list for his first studio album, The Bigger Artist.

BTS. The South Korean boy band isn't on the list for its hit EP, Love Yourself: Her.

Kodak Black. The rapper isn't on the list for his first full-length album, Painting Pictures.

Russ. The rapper isn't on the list for his debut album, There's Really a Wolf. He had released 11 prior mixtapes.

21 Savage. The rapper isn't on the list for his first studio album, Issa Album.

XXXTentation. The rapper isn't on the list for his first studio album, 17.

Young M.A. The female rapper isn't on the list for her first EP, Herstory.

Kehlani. The singer/songwriter wasn't eligible for her first full-length album, SweetSexySavage. She was nominated for Best Urban Contemporary Album two years ago for her mixtape You Should Be Here. Artists are no longer eligible once they have received a Grammy nomination. That also disqualified the next six artists on this list.

Childish Gambino. The multi-media star wasn't eligible for his third studio album, "Awaken My Love!" He had two nominations three years ago—Best Rap Album and Best Rap Performance.

Halsey. The pop singer wasn't eligible for her sophomore album, Hopeless Fountain Kingdom. She was nominated last year as a featured artist on The Chainsmokers' "Closer." She was also nominated as a featured artist on Justin Bieber's Purpose, an Album of the Year contender.

Bryson Tiller. The R&B star wasn't eligible for his sophomore album, True to Self. He was nominated for Best R&B Song last year for "Exchange."

Lil Yachty. The 21-year-old rapper wasn't eligible for his debut album, Teenage Emotions. He was nominated last year for Best Rap/Sung Performance for his featured role on D.R.A.M.'s "Broccoli."

Thomas Rhett. The country singer wasn't eligible for his third album, Life Changes. He was nominated for Best Country Song last year for "Die a Happy Man."

Jhené Aiko. The singer/songwriter wasn't eligible for her second studio album, Trip. She had three nominations three years ago—Best Urban Contemporary Album, Best R&B Song and Best Rap/Sung Collaboration.

Other Noteworthy Acts That Are Eligible

Kane Brown

Post Malone

Khalid

Luke Combs

SZA

Julia Michaels

James Arthur

Brett Young

Cardi B

Midland

Marian Hill

Playboi Carti

Cheat Codes

Bishop Briggs

Kaleo

Zara Larsson

Dua Lipa

Bebe Rehxa

Grace VanderWaal

Other New or New-ish Acts* That Are Not Eligible

Phantogram

Jo Jo

Meek Mill

The xx

Joey Bada$$

Father John Misty

Machine Gun Kelly

French Montana

Neck Deep

Dave East

Fifth Harmony

A$AP Mob

ODESZA

Dustin Lynch

Kip Moore

KYLE

Kygo

*defined as acts that have released three or fewer studio albums, the maximum allowed under the current rules.