If land can be owned – then it might seem obvious that if you own some land and build
a house on it, then that house is your property.
And if you plant a tree on your land, that tree is yours too.
But when that tree drops a leaf, and the leaf falls to the ground, do you own the falling
leaf?
When you build a chimney in the air on top of your house, you own the chimney.
So do you also own the smoke coming out?
And what about the plane flying overhead, is that on your property?
Who Owns The Sky?
It’s a fascinating question that has entertained and frustrated lawyers and judges for hundreds
of years.
In this video, we’re going to focus mostly on American law, but our story starts all
the way back in old-timey Britain in the 16th and 17th centuries when it was deemed illegal
for houses’ roofs to overhang your neighbour’s property.
These rulings were based on this old Roman maxim known as ad coelum for short.
What ad coelum means, is that whoever owns the soil, owns upwards to heaven and down
to hell.
In other words, you owned a cone from the centre of the earth, through the surface at
the boundaries of your property, and limitless into the universe.
This was never a Roman law, but did form the basis of English and American common law after
successive rulings throughout the following centuries.
A common law is a law that is not legislated by governments or politicians, but that is
based on precedent and case law from successive rulings of judges.
So, because land rights extended ad coelum, tree, houses and walls were all capable of
aerial trespass.
But of course things became more complicated with the advent of aircraft.
Between the late 1700s and early 1900s at first hot air balloons, then blimps, then
zeppelins, and of course, planes hit the scene.
In the early days of flight, aviators basically had the skies to themselves.
There was no regulation, and even though the maxim of ad coelum was still around, landowners
were more excited by the idea of human flight than they were worried about trespass, even
though it probably technically was a trespass for an aviator to fly over their neighbour’s
property, thanks to ad coelum.
But that didn’t stop lawyers worrying.
And because this was still before World War 1, it actually wasn’t perfectly clear whether
even countries themselves had sovereignty over their own airspace.
After all, similar international disputes regarding sovereignty over the sea were predominantly
leaning towards the sea being a place free for navigation.
Although the UN convention on the law of the sea was still decades away.
The sea and the sky aren’t really the same though.
For starters, gravity exists, so any items dropped even from a great height could cause
damage or intrusion on the ground.
While there were those that argued that airspace could never be possessed (Fauchille), with
the start of world war 1 and the threat that enemy aircraft posed, countries seized full
control and regulation over their own airspace as a matter of national security and public
expectation, rather than law.
This was enshrined after the war in the Convention Relating to International Air Navigation at
the Paris Peace conference, which confirmed every power’s “complete and exclusive
sovereignty over the air space above its territory“.
The US never actually ratified this international agreement, but did ratify its superseding
agreement in 1944, the Chicago Convention on International Civil Aviation.
It also made its own laws – and government sovereignty over all US airspace is today
enshrined in title 49 of the US Code.
So, back in the 1920s, it was accepted that countries controlled their own airspace – where
did that leave landowners?
If their rights extended ad coelum, could they charge for flying through their property?
And could they otherwise sue for trespass?
It would be more sensible just to make laws allowing planes to fly over private land,
and that’s exactly what Germany, France, Switzerland and the UK did.
And in the US, by the 1920s it was generally agreed that allowing overflight was a good
idea, but because of a pesky document called the constitution, the conundrum was how to
enact this.
The constitution protects the rights to property in the 5th and 14th amendments, so it was
feared that allowing planes to fly over private property could be contested as an unconstitutional
deprivation of property and liberty.
This lead to a sluggish rate of legal change in the US, particularly compared to the lightning
pace of technological development of aircraft.
With each passing year aircraft were becoming more advanced and more numerous, and as a
result, air commerce was booming.
So, the United States needed to do something, and between 1921 - 1922 the Uniform State
Law on Aeronautics was drafted.
This law permitted aircraft to fly over private land as long as they did not fly too low or
interfere with the landowners’ use of their property.
The problem with this law was in the name, this was a state law and was non-uniformly
adopted by just over 20 states within the next 10 years.
What it did do was deftly skirt the issue of constitutionality and ad coelum by asserting
that landowners did own their airspace, just with the proviso that aircraft also had the
right to fly through it.
This was similar to the way that rivers were treated under the law – they flowed through
private land, but the right of passage along them was preserved.
So with about half the states adopting this legislation, there was still no federal uniformity
within the US – until in 1926 when the Air Commerce Act made matters even more uncertain.
The constitution protects congress’s right to regulate interstate commerce, and it’s
on these grounds that the Air Commerce Act was enacted.
This upheld the freedom of navigation for planes over private property through navigable
airspace (that is, above the minimum safe flying altitude) but only for interstate and
international flights.
The same section of the constitution was already allowing for the government to regulate intrastate
commerce in the form of railroads, shipping and radio, and indeed the Act did include
regulations that were not specific to interstate air commerce, such as registration of pilots,
but on the question of land rights and trespass, only the rights of interstate and international
travel were considered.
That’s at least until 1938 when at last the Civil Aeronautics Act upgraded the Air
Commerce Act by extending the right of transit through navigable airspace to all flights,
not just interstate and international ones.
There are several really interesting cases from around this time, but for the sake of
the length of this video we will just talk about the big seminal moment in airspace case
law, Causby vs the US Government.
In 1945 a chicken farmer and their family sued the US government, after a military airport
next to their farm started flying planes at such low altitudes over their property that
their grandchild was kept up at night, they lived in fear that a plane would crash into
their house, and that their chickens became so startled at the sound of an airplane they
‘burst themselves open’ against the side of their coop.
Normally the US government can’t be sued unless Congress says it can, but they alleged
the government was in violation of the constitution, so they could sue for takings.
They alleged that by flying planes so low overhead, the government had effectively taken
their property from them, by taking away their private enjoyment of it, and effectively taking
away their chicken farming business – so they sued for just compensation.
The claim was heard initially in the lower courts, and finally in the Supreme Court 1946.
The Supreme Court found that “The landowner owns at least as much of the space above the
ground as he can occupy or use in connection with the land.”
And that landowners “must have exclusive control of the immediate reaches of the enveloping
atmosphere” above their land.
This basically asserted that landowners do own the airspace immediately above their property,
so it could be trespass to fly over someone else’s land at such a low altitude that
it prevents their enjoyment of their private property.
In the end the supreme court ruled that the government had taken the chicken farmers’
airspace.
So now the upper airspace was free for passage as per the civil aeronautics act (and the
air commerce act before it), and according to the supreme court the lower airspace, though
precisely how low was subjective, definitely belonged to the landowner.
So how much of the sky do you own?
You definitely don’t own all the way up to space, but aircraft can aerially trespass
if they fly so low as to interfere with your enjoyment of your property.
But to put an exact height limit on it?
That much is complicated.
This issue of sovereignty above us is far from solved.
The advent of space travel has raised difficult questions around the upper boundary of state
sovereignty in the sky, and the proliferation of drones closer to the ground will no doubt
increase the discussion around aerial trespass.
Let me know what you think about sovereignty above the ground, in the sky, and in space.
Where should the boundaries be?
And should people own the sky?
If not, what other systems might work?
And if you really want to impress your friends and family with knowledge of ancient common
law – and support the channel – you can also get one of these ad coelum T-shirts which
I designed – links below.
Thanks for watching, and see you next time.