Question: When did the political party that holds the majority in the political body that passed a bill giving regulators discretion to prohibit proprietary trades, gain control of the House?

Knowledge 1: Tanzania
The U.S. Senate passed a reform bill in May 2010, following the House which passed a bill in December 2009. These bills must now be reconciled. The New York Times provided a comparative summary of the features of the two bills, which address to varying extent the principles enumerated by the Obama administration. For instance, the Volcker Rule against proprietary trading is not part of the legislation, though in the Senate bill regulators have the discretion but not the obligation to prohibit these trades. [SEP] Knowledge 2: Party leaders of the United States Senate
The Senate is currently composed of 51 Republicans, 47 Democrats, and 2 independents, both of whom caucus with the Democrats. [SEP] Knowledge 3: United States House of Representatives
The presiding officer is the Speaker of the House, who is elected by the members thereof and is therefore traditionally the leader of the controlling party. He or she and other floor leaders are chosen by the Democratic Caucus or the Republican Conference, depending on whichever party has more voting members. The House meets in the south wing of the United States Capitol.
Knowledge 1: Tanzania
The U.S. Senate passed a reform bill in May 2010, following the House which passed a bill in December 2009. These bills must now be reconciled. The New York Times provided a comparative summary of the features of the two bills, which address to varying extent the principles enumerated by the Obama administration. For instance, the Volcker Rule against proprietary trading is not part of the legislation, though in the Senate bill regulators have the discretion but not the obligation to prohibit these trades. [SEP] Knowledge 2: Party leaders of the United States Senate
The Senate is currently composed of 51 Republicans, 47 Democrats, and 2 independents, both of whom caucus with the Democrats. [SEP] Knowledge 3: 2010 United States House of Representatives elections
Republicans regained control of the chamber they had lost in the 2006 midterm elections, picking up a net total of 63 seats and erasing the gains Democrats made in 2006 and 2008. Although the sitting U.S. President's party usually loses seats in a midterm election, the 2010 election resulted in the highest loss of a party in a House midterm election since 1938, and the largest House swing since 1948. This also happened to be the Republicans' largest gain in House seats since 1938. Republicans gained the most in New York state where they picked up six seats, defeating five incumbents and winning an open Democratic district. The heavy Democratic Party losses were attributed to anger with President Obama, opposition to the Affordable Care Act, large budget deficits and the weak economy. This was also the third consecutive midterm election in a president's first term where the Republican Party has made gains in the House of Representatives, as well as the second consecutive midterm election where party control of the said chamber changed hands. Notable freshmen included future Senators Cory Gardner, Todd Young, James Lankford, and Tim Scott, future Governor of Delaware John Carney, future Director of the Office of Management and Budget Mick Mulvaney, future Secretary of State Mike Pompeo, future Lieutenant Governor of Arkansas Tim Griffin, and future Louisiana Attorney General Jeff Landry.
Knowledge 1: Tanzania
The U.S. Senate passed a reform bill in May 2010, following the House which passed a bill in December 2009. These bills must now be reconciled. The New York Times provided a comparative summary of the features of the two bills, which address to varying extent the principles enumerated by the Obama administration. For instance, the Volcker Rule against proprietary trading is not part of the legislation, though in the Senate bill regulators have the discretion but not the obligation to prohibit these trades. [SEP] Knowledge 2: 2010 United States House of Representatives elections
Republicans regained control of the chamber they had lost in the 2006 midterm elections, picking up a net total of 63 seats and erasing the gains Democrats made in 2006 and 2008. Although the sitting U.S. President's party usually loses seats in a midterm election, the 2010 election resulted in the highest loss of a party in a House midterm election since 1938, and the largest House swing since 1948. This also happened to be the Republicans' largest gain in House seats since 1938. Republicans gained the most in New York state where they picked up six seats, defeating five incumbents and winning an open Democratic district. The heavy Democratic Party losses were attributed to anger with President Obama, opposition to the Affordable Care Act, large budget deficits and the weak economy. This was also the third consecutive midterm election in a president's first term where the Republican Party has made gains in the House of Representatives, as well as the second consecutive midterm election where party control of the said chamber changed hands. Notable freshmen included future Senators Cory Gardner, Todd Young, James Lankford, and Tim Scott, future Governor of Delaware John Carney, future Director of the Office of Management and Budget Mick Mulvaney, future Secretary of State Mike Pompeo, future Lieutenant Governor of Arkansas Tim Griffin, and future Louisiana Attorney General Jeff Landry. [SEP] Knowledge 3: United States House of Representatives
The presiding officer is the Speaker of the House, who is elected by the members thereof and is therefore traditionally the leader of the controlling party. He or she and other floor leaders are chosen by the Democratic Caucus or the Republican Conference, depending on whichever party has more voting members. The House meets in the south wing of the United States Capitol.

Answer: the 2010 election