[All links lead to Portuguese language pages, except when otherwise noted.]
On the heels of a landmark corruption case [en] in Brazil that saw former members of ex-President Luiz Inácio Lula da Silva's government convicted of participating in a vote-buying scheme, a proposed constitutional amendment in Brazil would hand over much of the investigative powers of the public prosecutors’ office, which prosecuted that case, to police.
Under discussion in the House of Representatives, the proposed amendment [en], dubbed by critics as the “bill of impunity”, aims to restrict the authority of carrying out criminal investigations to police. Currently, the prosecutors’ office can lead investigations just like police can, a measure enacted [en] after Brazil's military dictatorship to counter the country's culture of corruption with another level of accountability.
Former Police Commissioner and Federal Deputy Lourival Mendes, who authored the proposal, has defended  the amendment, saying that one institution, not two or more, should be in charge of investigations. The Public Ministry [en], as the federal public prosecutors’ office is called, should be limited to prosecuting cases that originate from evidence gathered by the police, according to Mendes.
But the independence of the prosecutors’ office has paved the way for many major cases, such as the prosecution of former Judge Nicolau dos Santos Neto  who was convicted of bribery, embezzlement, fraud, and money laundering in 2006, as prosecuting attorney Janice Ascari (@JaniceAscari ) highlighted  on Twitter:
Many institutional bodies would be affected by the so-called PEC 37, including the Secretariat of the Federal Revenue of Brazil  [en], the Brazilian Institute of Environment and Renewable Natural Resources  [en], and the Central Bank of Brazil  [en], but it is the Public Ministry which has spoken out against the measure most, headquartering their mobilization on the website Brasil Contra a Impunidade  [Brazil Against Impunity].
An Avaaz  petition has already gathered more than 96,000 signatures opposing the proposed amendment as of May 4, 2013, and the prosecutors’ office in the Brazilian state of Ceará has released a song  supporting cause.
On April 22, 2013, the prosecutors’ office in the state of São Paulo called for protest against the amendment on Twitter. Using the hashtags #NãoPEC37  and #PEC37 , many Twitter users have spoken out their opinions on the subject.
Some police organizations are leading campaigns in defense of the amendment, such as the National Association of the Federal Police Commissioners and the Association of the Police Commissioners of Brazil, which is responsible for the website PEC da legalidade  [PEC of legality].
@FCGaristo : In the FEDERAL POLICE force, only police commissioners advocate in favor of the DISGUSTING #PEC37  – 90% of the Federal Police are against this Shameful PEC which defends corruption! !
Journalist Decio Neves (@DecioNeves ) pointed out  one of the possible motivations behind legislators voting in favor of the proposal in a special committee of the House of Representatives, where the PEC 37 was approved with 14 votes on November 21, 2012:
@DecioNeves : TO LEGISLATE FOR THEIR OWN CAUSE: From the 14 deputies who approved the #PEC37  nine are being prosecuted with the assistance of the Public Ministry http://twitpic.com/ck95kf 
@todolho : Na votação da PEC37 se verá quem é quem. Corruptos serão pró. Os ainda com esperança de salvação votarão contra.
@todolho : We will see who is who in the PEC 37 voting session. Corrupt will be in favor of it. Those who do still have hope of salvation will vote against it.