In the mid-70s, a music scholar, maybe a professor, definitely someone we’d now call a ‘musicologist,’ wrote an alarming letter to Rolling Stone magazine. He stated that, by his estimation, within a few years the notes would run out. That is, musicians were about to exhaust all available music notes in every possible timing and context. He warned that soon there would be no more original songs. 

Beneath this letter was a response from John and Yoko. They were apparently enlisted by Rolling Stone to address this crisis. Their two-word reaction to song-pocalyspe: “Lighten up.“

I should point out that I can’t verify this happened. I saw the exchange printed somewhere many years ago, but I can’t find evidence online. Regardless, it’s no surprise that for decades music intellectuals have raised concerns about a limit on new songs. And that the songwriters have always reacted with a shrug.

The notes are only part of a song. Also critical: instrumentation, dynamics, performance texture, tempo, studio trickery — the list goes on. Those notes don’t seem as limited when we take these extra elements into consideration. But it’s still reasonable to imagine a few people coming up with similar melodies. And if some of those other elements align, then there might be a raised eyebrow or two. Is it plagiarism?

I’m not saying everyone is innocent of copying notes or lyrics or songs outright. But we’re led to believe it intentionally happens a lot less than it does. A dirty little secret is that songwriting isn’t all that difficult if you know what you’re doing. Having a ‘hit’ song is tough, but all of those elements I mentioned above — and some additional ones, like charisma and promotional budgets — contribute to making it a hit, too. When you think about all the potential downsides, it’s a lot easier to write a song than steal someone else’s.  

Minneapolis-based ‘record selector’ Mike 2600 has an amusing YouTube series called Songs That Sound The Same. Using two turntables (and I suspect some pitch manipulation), he goes beyond the ‘mash-up,’ drawing attention to songs that share an uncanny resemblance. This one‘s a lot of fun. As is this one and this one. 

A lot of Mike 2600’s comparisons rest on similarities in chord changes and sequences, a chord being a combination of usually three notes providing a bed for melody. Combinations of chords are a lot more limited than those of individual notes. There are a lot of similarities out there for Mike 2600 to choose from.

Mike 2600 could do one of these videos for “Stairway To Heaven” and Spirit’s “Taurus.” Maybe he has, but probably not — that resemblance is so well known it’s low-hanging fruit. Journalist Michael Skidmore thought he’d reach for that fruit when he filed a plagiarism suit on behalf of the late Spirit frontman Randy Wolfe. The two songs’ similarity elicited murmurings since the release of “Stairway To Heaven,” but the lawsuit didn’t appear until 2014. 

Yes, the iconic opening riff of “Stairway To Heaven” is bizarrely similar to “Taurus.” But so are a lot of things. The same descending chromatic chords, as noted in defense arguments, are found in the music of JS Bach and Henry Purcell, and also the song “Chim Chim Cher-ee” from Mary Poppins (which puts Led Zeppelin in an unlikely context). There are only so many chords used in so many ways.

Last week, judges agreed and cleared Led Zeppelin of wrong-doing. But the ruling added another twist — the court’s dismissal of ‘the inverse ratio rule.’ What’s that, and why is it interesting? Let’s dig in.

Understand that plagiarism doesn’t have to be intentional to warrant legal punishment. If it’s believed that you heard a song anytime and anywhere, then the plaintiff can argue it’s possible that plagiarism occurred, whether you meant to do it or not. The more famous a song is the easier it is to make this argument. George Harrison encountered this notion when “My Sweet Lord” was accused of copying The Chiffon’s “He’s So Fine.” The latter was a massive hit in 1963, at the same time The Beatles were making no secret of their admiration for American R&B. So the jury was convinced that Harrison, at the very least, unconsciously copied that song. 

This idea of access and sublimation came to its ridiculous conclusion in the recent case of Flame vs. Katy Perry. In my opinion, that case was already absurd, involving two somewhat similar and short melodic phrases representing modern pop’s zeitgeist. But Flame’s attorney argued that since his client’s song had 6 million online plays — spread out among platforms like YouTube and, yes, MySpace — it was undoubtedly, at some point, heard by the writers of Perry’s song. The jury ended up agreeing. 

Taken further, it seems the internet demolished the limitations of access. It’s now presumed that everything is available — how are 6 million streams on YouTube any different than an emerging artist appearing on an obscure but influential Spotify playlist? Arguably the potential for accidental thievery is the same. Almost all music is available by tapping the screen of a smartphone, so the idea of access is passé. The court in Led Zeppelin’s case recognized this change in our culture, and the ‘inverse ratio rule’ — which gave preference to the more widely distributed song — is toast.

There are other ways that technology alters our concepts of plagiarism. Let’s consider how companies like Splice are affecting musical ownership. Splice is a market-place for sounds, where recording artists can download loops and phrases to use in their own songs. After paying a subscription fee, the user is given these sounds as ‘royalty-free’ sonic building blocks. That means an artist can use these bits in a commercial recording without royalties or attribution to Splice, and claim the rights to the song as her own. No one owns Splice’s sounds — they can be used simultaneously in any number of songs. 

Of course, this model reached an inevitable outcome. A melodic loop from Splice was used in a song by — of all people — Justin Bieber. Within 24 hours of that song’s release, artist Asher Monroe accused Bieber of ripping off the instrumental hook from his song. But they both got the phrase from Splice. As did many other artists, including Korean hip-hop artist YUMDDA. According to The Verge, that leads to another 21st-century problem:

Because Monroe and YUMDDA’s songs have portions with the unaltered sample and nothing else, Shazam gets confused. The app sometimes identifies Monroe’s track as YUMDDA’s, and vice versa. But it has no trouble identifying Bieber’s song, likely because there are other percussive elements always layered on top of the sample.

And now here’s something else:

Damien Riehl — a lawyer, coder, and musician — and Noah Rubin pulled an impressive stunt. They wrote a program to generate every possible melodic combination of notes. The program then stored all 68.7 billion melodies to a hard drive. But rather than using up all the songs, as the Rolling Stone letter-writing musicologist feared, Damien and Noah put the contents of the hard drive in the public domain. All melodies are now free to use, they argued. From here forward, lawsuits for copyrighted note sequences are all frivolous. 

Of course, Damien and Noah’s effort is meant to make a statement and probably won’t change anything. The Led Zeppelin ruling will have more effect on songwriters (as will the appeal-in-progress on the Katy Perry suit). But it makes an interesting point. And it helps highlight the limited nature (and mathematics) of notes, and how subconscious plagiarism could become an outdated concept now that we’re subconsciously consuming everything. 

UPDATE: Soon after I wrote this post, Katy Perry and her co-writers won their appeal and the judge overturned the plagiarism ruling.

This post was adapted from Ringo Dreams of Lawn Care, a weekly newsletter loosely about music-making, music-listening, and how technology changes the culture around those things. Click here to check out the latest issue and subscribe.