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Regulation of Speech and Media Coverage of Corruption: An Empirical Analysis of the Mexican Press

ACRN Research Correspondent Brigitte Zimmerman reviews an article by Piero Stanig that considers the effect of legislation restricting media freedom on corruption media coverage.

Stanig aims to provide direct evidence of a key mechanism underpinning much of anti-corruption theory regarding the media: that inhibiting media freedom prevents access to information about corruption. Through rigorous and innovative methods, he thoroughly provides evidence of this effect: areas with more stringent regulation experience 40% fewer corruption stories.

The research addresses an untested but critically important assumption in the literature, and Stanig combines extensive field research with creative methods in order to do so. There are only two questions that occurred to me as I was reading the manuscript. First, Stanig has compelling disaggregated data for both his primary dependent variable (corruption coverage) and his independent variable (regulation). It would have been extremely interesting to explore more micro-level effects in both of these variables. Is there any evidence of a curvilinear relationship between regulation and information availability, for example? Do certain types of information – vote buying, perhaps – fall prey to regulation more than others?

Also, Stanig claims that his design offers strong causal identification because the variation in regulation is at the sub-national level in Mexico, where many features – except for press freedom – are held constant. It seems likely this is true for many observable sources of variation that may affect press regulation. However, one still wonders about omitted variables that vary at the sub-national level in Mexico and may be “root causes” of variation in press freedom. For example, there is sorting of journalists in several of the countries I study: the most “eager to please” journalists go to the most tightly regulated areas and cover the most controversial topics. The legislation shifts the geographic distribution of information, but not the overall level of information. Stanig reassures me somewhat in his use of instruments, but does not thoroughly explain why he believes violations of the exclusion restriction are unlikely. These are not extremely concerning issues, but rather musings that might be avenues for future research.


Restrictions to media freedom, in the form of repressive defamation legislation, are thought to affect the amount of information about corruption that the media report. Exploiting variation in regulation of speech across states in a federal country, Mexico, and using a novel data set based on content analysis of the local press, I estimate the effect of lack of freedom on the coverage devoted to acts of malfeasance by public officials. Corruption receives significantly less attention in states with a more repressive defamation law. Instrumental variable models corroborate the interpretation of the negative association between regulation and coverage as a causal “chilling effect.”


P. Stanig, Regulation of Speech and Media Coverage of Corruption: An Empirical Analysis of the Mexican Press. American Journal of Political Science, 59(1): 175-193 (2015).

Author : Piero Stanig

05 Mar 2015

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Institution(s): UCSD. Research Field: political economy of corruption

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