Thailand witnessed the two most violent elections in modern Thai history in the 2001 and 2005 elections. The number of incidents, death toll and injuries surpassed other elections’ records. Meanwhile, the intensity of electoral violence significantly dropped in the 2007 and 2011 elections (see table 1). The 2007 election was, in fact, one of the most peaceful elections in Thailand. Compared to constant levels of violence from 1979 to 1997, there was sharp fluctuation over the period 1997-2011. Major structural and institutional changes that came into effect after 1997 (constitution, electoral and party system, civil-military relations, and political party-social movement linkages) caused these ups and downs.
The period from 1997 to 2011 was highly transformative and turbulent for Thai politics and society. Within one decade, there were five elections (including the nullified 2006 election), six prime ministers, two constitutions, one military coup, and countless violent clashes between state security forces and color-coded mass movements which led to a large number of deaths and injuries. Parliamentary democracy and electoral institutions underwent a dramatic change. Initially, the new constitution and political reform produced a strong and stable civilian administration and political party structure. Programmatic politics and policy- based campaigning played increasingly important roles in shaping electoral outcomes, even though the particularistic elements of patronage, pork, personality, and coercive force still existed. Political party and electoral institutions were, more than ever, strengthened and meaningfully connected to a majority of the electorate. Direct elections at the local level enabled by decentralization helped created stronger linkages between the electorate and elected politicians.
However, the military coup in 2006 derailed the legitimacy and development of parliamentary democracy. The traditional royal-military-bureaucratic power alliance, which lost its power but had no willingness to participate in electoral competition, employed an old-fashioned, coercive tool (the coup) to capture state power and overthrow the popularly elected government. The 2006 coup profoundly transformed Thai politics; it polarized the country, exacerbated political divisions, and radicalized political participation. As a result, electoral competitions were infused with ideological contestation, rather than only particularistic or programmatic campaigns. The changing rules, landscape and power structure of Thai politics at the national level strongly effected local political settings—the balance of power between political groups and families, and between national parties and local bosses. And the political changes at the local level, structured by national dynamics, shaped the supply and demand of coercion and electoral violence witnessed in this period.
In 2014 Elections, the poll was marred by violence which was elevated from individual targeted violence to a more organized system targeting to interrupt the whole election process. It was a result from a long protest of the opposition side to call for political reform before elections. Of the 375 constituencies nationwide, 92 voting-related incidents were reported. The 2014 Election was eventually nullified by the Constitutional Court.
Source :
http://www.cityu.edu.hk/searc/Resources/Paper/14061615_154%20-%20WP%20-%20Dr%20Prajak.pdf
http://edition.cnn.com/2014/02/02/world/asia/thailand-election/