## 4 Privacy and Open Government
### Big Data, Open Government and Privacy  
A third privacy issue relates to the release of government data through open data programs within the broader big data context. \"Big data\" is a term used to refer to the massive and ever-expanding volume of digital data [60, 61]. Although government data sets may, on their own be \"small data\" [62], when released as open data they enter the big data eosphere. Such data sets, made publicly available in reusable digital formats, may appear to be free of personal information or may have been anonymized. Nevertheless, their use in combination with other available data, can pose real risks to privacy. Sophisticated algorithms can be used to match these different data sets and to re-identify specific individuals, contributing to widespread practices around profiling of individuals [63, 64]. The oft-cited examples of the release of anonymized customer data by both AOL and by Netflix [64, 65] illustrate how the many minds that are the engine of Web 2.0 can, working alone or in combination, quickly lead to the identification of specific individuals in anonymized data sets based upon pattern identification and data matching. Ironically, anonymization, while protecting privacy, may undercut the usefulness of the data. As [PERSON] notes, \"Data can either be useful or perfectly anonymous but never both\" [64] (p. 1704). Thus the objective of open data--the release of useful data sets in reusable formats--does not always sit easily with privacy principles. Public sector data protection laws define personal information broadly, and most definitions will include information that does not directly identify an individual, but that may lead to such identification [66, 67]. As a result, there is a real risk that open data initiatives may lead to breaches of data protection obligations. This has raised concerns that privacy laws may actually be in tension with the potential benefits of open data [31]. At the same time, the massive release of government data through open data programs may add further fuel to the insatiable engines of big data, and thus may further undermine the control that individuals are meant to have over their personal information. While transparency and accountability are touted as prime motivators for open government, the language of entrepreneur and innovation is also clearly present in the rhetoric around open government [4, 18]. While many users of open data are interested in building apps and tools based on government data, there is nothing to prevent the use of open data in profiling, data mining, and other activities which have privacy implications for individuals. The re-identification and profiling risks related to open government data are only likely to intensify as governments at all levels diversify and amplify the information they collect. Popular concepts such as \"smart cities\" or \"intelligent transportation\" envisage an environment in which all manner of data about individual activities is collected and recorded either by government entities or by the private sector service suppliers with which they have contracted. Although the primary objectives may be to improve services or planning, the data will be highly sought after by the private sector and by researchers for a broad range of purposes. The release of such data, even if anonymized, may only serve to enhance privacy risks. Yet, as noted earlier, privacy restrictions on open data may undermine data quality, hampering re-use of the data, or blunting transparency and accountability. This third consideration--the impact of big data on privacy in the context of open government--raises concerns about the extent to which government data will contribute to increased profiling of individuals or to the re-identification of specific individuals. These are clearly privacy risks; the challenge is to assess these risks in light of the benefits of potentially greater transparency and accountability, improved services, and increased innovation.