Legal implications
In 1992, Hungarian youths Gábor Takács and Róbert Dallos, both then 17, were the first people to face legal action after creating a crop circle. Takács and Dallos, of the St. Stephen Agricultural Technicum, a high school in Hungary specializing in agriculture, created a 36-metre (118 ft) diameter crop circle in a wheat field near Székesfehérvár, 43 miles (69 km) southwest of Budapest, on June 8, 1992. On September 3, the pair appeared on Hungarian TV and exposed the circle as a hoax, showing photos of the field before and after the circle was made. As a result, Aranykalász Co., the owners of the land, sued the teens for 630,000 Ft (~$3,000 USD) in damages. The presiding judge ruled that the students were only responsible for the damage caused in the circle itself, amounting to about 6,000 Ft (~$30 USD), and that 99% of the damage to the crops was caused by the thousands of visitors who flocked to Székesfehérvár following the media's promotion of the circle. The fine was eventually paid by the TV show, as were the students' legal fees.
In 2000, Matthew Williams became the first man in the UK to be arrested for causing criminal damage after making a crop circle near Devizes. In November 2000, he was fined £100 and £40 in costs. As of 2008, no one else has been successfully prosecuted in the UK for criminal damage caused by creating crop circles.
Creation
The scientific consensus on crop circles is that they are constructed by human beings as hoaxes, advertising, or art. The most widely known method for a person or group to construct a crop formation is to tie one end of a rope to an anchor point and the other end to a board which is used to crush the plants. Sceptics of the paranormal point out that all characteristics of crop circles are fully compatible with their being made by hoaxers.
Bower and Chorley confessed in 1991 to making the first crop circles in southern England. When some people refused to believe them, they deliberately added straight lines and squares to show that they could not have natural causes. In a copycat effect, increasingly complex circles started appearing in many countries around the world, including fractal figures. Physicists have suggested that the most complex formations might be made with the help of GPS and lasers. In 2009, a circle formation was made over the course of three consecutive nights and was apparently left unfinished, with some half-made circles.
The main criticism of alleged non-human creation of crop circles is that while evidence of these origins, besides eyewitness testimonies, is essentially absent, some are definitely known to be the work of human pranksters, and others can be adequately explained as such. There have been cases in which researchers declared crop circles to be "the real thing", only to be confronted with the people who created the circle and documented the fraud, like Bower and Chorley and tabloid Today hoaxing Pat Delgado, the Wessex Sceptics and Channel 4's Equinox hoaxing Terence Meaden, or a friend of a Canadian farmer hoaxing a field researcher of the Canadian Crop Circle Research Network In his 1997 book The Demon-Haunted World: Science as a Candle in the Dark, Carl Sagan concludes that crop circles were created by Bower and Chorley and their copycats, and speculates that UFOlogists willingly ignore the evidence for hoaxing so they can keep believing in an extraterrestrial origin of the circles. Many others have demonstrated how complex crop circles can be created. Scientific American published an article by Matt Ridley, who started making crop circles in northern England in 1991. He wrote about how easy it is to develop techniques using simple tools that can easily fool later observers. He reported on "expert" sources such as The Wall Street Journal, who had been easily fooled and mused about why people want to believe supernatural explanations for phenomena that are not yet explained. Methods of creating a crop circle are now well documented on the Internet.
Some crop formations are paid for by companies who use them as advertising. Many crop circles show human symbols, like the heart and arrow symbol of love, stereotyped alien faces,
Hoaxers have been caught in the process of making new circles, such as in 2004 in the Netherlands for example.
Advocates of non-human causes discount on-site evidence of human involvement as attempts to discredit the phenomena. Some even argue a conspiracy theory, with governments planting evidence of hoaxing to muddle the origins of the circles. When Ridley wrote negative articles in newspapers, he was accused of spreading "government disinformation" and of working for the UK military intelligence service MI5. Ridley responded by noting that many cereologists make good livings from selling books and providing high-priced personal tours through crop fields, and he claimed that they have vested interests in rejecting what is by far the most likely explanation for the circles.
In serious science magazines from the 80s and 90s, for example Science Illustrated, one could read reports on that the plants were bent by something that could be microwave radiation, rather than broken as they would become by physical impact. The magazines also contained serious reports of the absence of human influence and measurement of unusual radiation. Today, this is considered to be pseudoscience, while at the time it was subject of serious research. At that time, it was also more likely that an unknown factor was behind the incidents, not least seen in light of the fact that GPS was not available to the public.
Alternative explanations
Weather
It has been suggested that crop circles may be the result of extraordinary meteorological phenomena ranging from freak tornadoes to ball lightning, but there is no evidence of any crop circle being created by any of these causes.
In 1880, an amateur scientist, John Rand Capron, wrote a letter to the editor of journal Nature about some circles in crops and blamed them on a recent storm, saying their shape was "suggestive of some cyclonic wind action".
In 1980, Terence Meaden, a meteorologist and physicist, proposed that the circles were caused by whirlwinds whose course was affected by southern England hills. As circles became more complex, Terence had to create increasingly complex theories, blaming an electromagneto-hydrodynamic "plasma vortex". The meteorological theory became popular, and it was even referenced in 1991 by physicist Stephen Hawking who said that, "Corn circles are either hoaxes or formed by vortex movement of air". The weather theory suffered a serious blow in 1991, but Hawking's point about hoaxes was supported when Bower and Chorley stated that they had been responsible for making all those circles. By the end of 1991 Meaden conceded that those circles that had complex designs were made by hoaxers.
Paranormal
Since becoming the focus of widespread media attention in the 1980s, crop circles have become the subject of speculation by various paranormal, ufological, and anomalistic investigators ranging from proposals that they were created by bizarre meteorological phenomena to messages from extraterrestrial beings. There has also been speculation that crop circles have a relation to ley lines. Many New Age groups incorporate crop circles into their belief systems.
Some paranormal advocates think that crop circles are caused by ball lighting and that the patterns are so complex that they have to be controlled by some entity. Some proposed entities are: Gaia asking to stop global warming and human pollution, God, supernatural beings (for example Indian devas), the collective minds of humanity through a proposed "quantum field", or extraterrestrial beings.
Responding to local beliefs that "extraterrestrial beings" in UFOs were responsible for crop circles appearing, the Indonesian National Institute of Aeronautics and Space (LAPAN) described crop circles as "man-made". Thomas Djamaluddin, research professor of astronomy and astrophysics at LAPAN stated, "We have come to agree that this 'thing' cannot be scientifically proven." Among others, paranormal enthusiasts, ufologists, and anomalistic investigators have offered hypothetical explanations that have been criticized as pseudoscientific by skeptical groups and scientists, including the Committee for Skeptical Inquiry. No credible evidence of extraterrestrial origin has been presented.
Animal activity
In 2009, the attorney general for the island state of Tasmania stated that Australian wallabies had been found creating crop circles in fields of opium poppies, which are grown legally for medicinal use, after consuming some of the opiate-laden poppies and running in circles.
Changes to crops
A small number of scientists (physicist Eltjo Haselhoff, the late biophysicist William Levengood) have found differences between the crops inside the circles and outside them, citing this as evidence they were not man-made.
Levengood published papers in journal Physiologia Plantarum in 1994 and 1999. In his 1994 paper he found that certain deformities in the grain inside the circles were correlated to the position of the grain inside the circle. In 1996 sceptic Joe Nickell objected that correlation is not causation, raised several objections to Levengood's methods and assumptions, and said "Until his work is independently replicated by qualified scientists doing 'double-blind' studies and otherwise following stringent scientific protocols, there seems no need to take seriously the many dubious claims that Levengood makes, including his similar ones involving plants at alleged 'cattle mutilation' sites." (in reference to cattle mutilation).
Magnetism
In 2000, Colin Andrews, who had researched crop circles for 17 years, stated that while he believed 80% were man-made, he thought the remaining circles, with less elaborate designs, could be explained by a three-degree shift in the Earth's magnetic field, that creates a current that "electrocutes" the crops, causing them to flatten and form the circle.
Folklore
Researchers of crop circles have linked modern crop circles to old folkloric tales to support the claim that they are not artificially produced. Circle crops are culture-dependent: they appear mostly in developed and secularized Western countries where people are receptive to New Age beliefs, including Japan, but they don't appear at all in other zones, such as Muslim countries.
Fungi can cause circular areas of crop to die, probably the origin of tales of "fairie rings". Tales also mention balls of light many times but never in relation to crop circles.
A 17th-century English woodcut called the Mowing-Devil depicts the devil with a scythe mowing (cutting) a circular design in a field of oats. The pamphlet containing the image states that the farmer, disgusted at the wage his mower was demanding for his work, insisted that he would rather have "the devil himself" perform the task. Crop circle researcher Jim Schnabel does not consider this to be a historical precedent for crop circles because the stalks were cut down, not bent. The circular form indicated to the farmer that it had been caused by the devil.
In the 1948 German story Die zwölf Schwäne (The Twelve Swans), a farmer every morning found a circular ring of flattened grain on his field. After several attempts, his son saw twelve princesses disguised as swans, which took off their disguises and danced in the field. Crop rings produced by fungi may have inspired such tales since folklore holds these rings are created by dancing wolves or fairies.