Im writing this in response to the fantastic post created by 
https://mises-media.s3.amazonaws.com
As Murray Rothbard explained, all rights are property rights. But a property right is simply the exclusive right to control a scarce resource. There are two types of scarce resources: human bodies and external resources found in nature. Ideas can hardly be considered scarce. Therefore, all property rights refer to physical property.
While there are many different types of IP, I am going to focus on the two most prevalent and well known: copyright and patents. Rothbard also postulated that copyright is good and patents are bad in that a copyright is simply one's exclusive right to sell an invention and a patent is the government saying that one has exclusive right to the invention itself. (Think Alexander Grahm Bell and the telephone.) For a copyright to be violated one would have to prove that the inventor in question had access to the original inventors copyrighted property. I think both are incompatible with a Free Market.
"Intellectual property is a State based haven of the weak, the stupid and those lacking confidence in their own ability."
-Ben Stone of badquaker.com
The history of patents goes back to monarchs issuing monopolies to favored people in order to get them indebted to the sovereign. The word patent comes from old Latin patente meaning open. So a patent was an open letter from a sovereign granting certain people monopolies that protected certain goods and services for a period of time.
In the 1500's one of the earliest uses of patents was to grant pirates the authority to become privateers. Francis Drake was given letter patent by Queen Elizabeth I to sail to America and plunder Spanish ships along the way. This was effectively "legal" piracy. We can see new age pirates today in the form of "patent trolls" or "patent privateers."
The history of copyright law is no less insidious. With its roots in censorship, churches and governments used copyrights to control the official and political narrative and suppress guilds as printing became easier and more available. Concerned with the spreading of ideas dangerous to those in power they would limit what printing guilds could produce through copyright laws.
Modern day, institutionalized IP laws don't require you to go to the king and ask for a monopoly. Now, one simply goes to the patent office. Companies apply for patents to have a weapon against other companies who would sue them with their patents. This effectively creates a barrier to entry for smaller companies when the larger ones cross licence and have protection from each other's competition.
An article in the American constitution, adopted in 1789, authorized Congress to "promote progress of science and useful arts by securing for a limited time to authors and inventors their exclusive right to their respective writings and discoveries." John Locke, who's writings influenced the founding fathers, as well as Thomas Jefferson, the first patent commissioner, had reservations about the idea of granting these monopolies. But they did anyway with the belief that it would encourage innovation.
Aa bad as this decision was, these men didn't see IP as a natural right. Even Locke didn't believe his idea of homesteading extended to ideas, only scarce resouces. So the argument that IP, said to be a property right, as a form of natural rights is unfounded. A natuarl right wouldn't expire. Nor would it apply to certain groups of people or exclude certain creations. This was a federal statute administered by a huge federal bureaucracy granting monopolies to Americans who apply to ask the courts to use federal force against competitors who are simply using information to guide the use of their actions.
http://www.sblaw.vn/wp-content/uploads/2016/07/Intellectual-Property
Copyrights and patents slow down modern ideas and their diffusion and stifles innovation rather than encouraging it. Pro IP arguments take a utilitarian perspective rather than principled perspective. The most common argument is that if government grants monopolies on certain types of innovation we'll get more of it and be more prosperous. (Create net wealth) However this claim isn't explicit because there haven't been anyone to show the net wealth.
Patents systems impose costs on society such as costs in salary, litigation, insurance, and higher costs for products. Supporters of IP would have to compare costs to net gain and come up with the difference. A better argument would be that you don't know because value is subjective. Same hies for gained and lost innovation.
IP laws impose a net cost on society to at least some degree and to some degree decreases innovation. The argument that stands to be the most important philosophically, in my opinion, is that IP laws are statutory schemes that can only be constructed by legislation. This being the case it would be logically inconsistent for supporters of a Free Market to simultaneously reject the legitimacy of the state and support legislation of intellectual property.
In short, instead of stifling innovation and growth with legislation, we should be free to create, share, innovate and prosper in a truly Free Market of entrepreneurs and inventors. This isnt to say that voluntary interaction couldn't come up with a solution that doesn't require force against competitors who are simply using information. Without the State these monopolies and corporations taking advantage of bullshit IP laws would be just an afterthought at best.
Thanks and laissez-faire,
Aahabb
Sources:
https://mises.org/library/case-against-ip-concise-guide
https://www.etymonline.com/word/patent
http://www.vonmisesinstitute-europe.eu/patent-privateering-patents-weapons/