MAC and IP Addresses: Personal Information?

by Dentons

[author: ]

A minor kerfuffle broke out at a recent (May 30, 2012) U.S. Federal Trade Commission workshop, “In Short: Advertising and Privacy Disclosures in a Digital World.” During a discussion of a privacy and advertising on mobile platforms, Sara Kloek, Director of Outreach for the Association for Competitive Technology, stated that a MAC address was information about a device and not personal information. Pam Dixon, founder and executive director of the World Privacy Forum, was quick to snap back stating that a MAC address was personal information.

Who is right? Why is it that we are still debating this fundamental issue? And is the answer different for IP addresses? This post is a bit longer than most here on but I’ll try to unpack these issues in the context of Canadian privacy laws and principles.

What’s a MAC address?

A Media Access Control address is an alpha-numeric number that is assigned to a hardware device that connects to a computer network. In simple terms, a MAC address is part of the addressing system that will allow one device to route packets of information to another device. I’m a lawyer and not a technologist but I think it is fair to say that the MAC address for my smart phone will, for example, be visible to a retailer operating a wireless network when I come within range of that network. The MAC address will be used by that wireless network when I connect to access the Internet or network services of that retailer.

Each device has a unique MAC address (leaving aside counterfeiting and spoofing). Therefore, the MAC address for the device may be harnessed as a unique identifier for more than network functionality when it is visible or when an application installed on my device inspects and relays the MAC address. So, a MAC address could be a potential gateway to collecting information on the activities of users of that device when connected to the Internet. (I wrote “users” deliberately because although there is probably only one user of my smart-phone, the same may or may not be true for any family’s laptop and other devices.)

A MAC address can also be used as a tool in tracking the movements of the device. For example, Wi-Fi access points will have a MAC address that can be mapped geographically. When a device (such as a smart-phone, tablet or laptop) interacts with a Wi-Fi network, the MAC address for that device will also be visible, thereby permitting anyone interacting with the device to determine the location of the device, provided that that person (a) knows the location of the Wi-Fi access point and (b) can see the MAC addresses of the access point and the device.

What’s an IP address?

An Internet Protocol address is a numerical label that is assigned to an addressable connection to the Internet. The IP address is also part of the addressing system (at a higher level than the MAC address). It is used in routing packets of information over the Internet. Again, I am not a technologist but my understanding is that, for most consumers, the IP address is probably not static or permanently assigned to their device. Instead, the IP address will be dynamic. The consumer’s Internet service provider will assign an IP address for a period of time, which might be reassigned to someone else after the consumer disconnects. However, an Internet service provider is able to correlate the IP address at a specific date and time to a subscriber to whom it is providing Internet service access, assuming it retains that information.

The issue gets a bit tricky when a wireless network router is involved. Take my home wireless network as an example. The router gateway to the Internet service provider may be assigned an IP address by the Internet service provider. That IP address may be changed from time to time. Each device connected to the home network will each have an individual IP address internally to the network system.

What’s personal information?

Personal information is defined in Canadian private sector privacy legislation as information about an identifiable individual. There are some exceptions, but that is the basic definition.

Although reasonable people can debate the point, one justification of privacy legislation – whether applicable to the private sector or the public sector – is that it is necessary to protect individuals from unreasonable surveillance. Indeed, there was a telling exchange at the FCC workshop mentioned at the outset of this post, when Pam Dixon said that the MAC address was personal information since, after all, it could be correlated to an individual and be subject to a subpoena.

Unreasonable surveillance may be viewed as inimical to personal liberty and potentially used as a tool of manipulation or, in its worst form, oppression. Even when an organization engages in surveillance for public good or passively without seeking to manipulate, some view this as a significant intrusion since the information obtained through that surveillance may be conscripted by the power of the state for other purposes.

The problem that privacy advocates face is that the gateway concept of “personal information”as currently drafted in Canadian privacy legislation is probably too amorphous in many cases to constrain systematic surveillance in a coherent way.

Thus, in a recent appellate case last year, theAlberta Court of Appeal concluded that in order for information to be about an “identifiable individual”, the person must be identifiable, the information must have a precise connection to an individual. In order to be “personal” the information must be about the individual–that is, directly related to the individual. Information did not become personal information simply by being associated indirectly with an individual through ownership. Without that limit, “virtually every object or property is connected in some way with an individual” and would become personal information.

So, a driver’s licence is personal information in Alberta but a licence plate is not. The driver’s licence is uniquely connected to a person. Indeed, the driver’s licence card functions in Canada as an identification card – that is, government issued identification. On the other hand, in Alberta, at least, a licence plate is connected to the vehicle and only linked through a database to an individual. Reasonable people can debate the Alberta decision and whether other appellate courts should follow when the issue arises.

So what’s the answer?

In one sense, the answer is easy. The Office of the Privacy Commissioner of Canada considers that an IP address may constitute personal information if the IP address is associated with or linked to an identifiable individual.

Similarly, in a commendable and comprehensive study of the issues, the Information and Privacy Commissioner of Ontario and Kim Cameron argue that MAC addresses, as unique identifiers, may be linked to individuals and, therefore, may constitute personal information.

The precautionary principle suggests that organizations should treat MAC and IP addresses as personal information. However, in many (most?) cases, MAC and IP addresses may not be directly linked to individuals. An Internet service provider will be able to associate the IP address to a home or business account but not (at least in the ordinary course) to any particular person using a device linked to the Internet, particularly if we are talking about my access to the Internet through a WiFi system at a coffee shop. A MAC address does not disclose who actually has possession of the device. However, there is a greater probability of correlation between the owner of the device and the MAC address than there is of an IP address and an individual.

So we are back to where we always are with personal information. A MAC address or an IP address information is rarely going to be in and of itself information about an identifiable individual in the sense of having a precise connection and being directly related to an identifiable individual. It is the context of how the MAC address or IP address is combined with other information (or could be reasonably be combined with other information) that has privacy advocates concerned. In each case, of course, if you knew and combined enough on-line and off-line information you might have enough data to make a highly probably guess about who was doing what and where. But the same could be said about a licence plate number.

So who was correct (from a Canadian perspective) at the FTC workshop? Both. In and of itself, a MAC address (and an IP address) are likely not personal information but they are rich gateways to the collection and the accumulation of data points that can transform them into personal information if privacy (anti-surveillance) measures are not built into the technologies using these addresses. Ultimately, what is personal information is fundamentally determined by context. The debate will continue.


DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

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