The reaction of the socialist left to the 'homosexual question' has a rich and varied trajectory, I will attempt to provide a brief outline to some of the main themes. In order to understand the nature of the left's reaction to the issue of what we would now term 'gay rights', an understanding the historical contexts occasioning the call or protection of marginalized sexual minorities is needed.
At the end of the 19th century there occurs a particular tightening of laws in reference to 'homosexual' or same-sex sex acts, this is expressed in the UK in the form of the Criminal Law Amendment Act of 1885 and within Germany via Paragraph 175 of the German Legal code.
Paragraph 175 of the German Legal code introduced a provision of the German Criminal code from 1871 onwards punishing "unnatural fornication" among "persons of the male sex" as a criminal offense punishable by imprisonment and potential "loss of civil rights".
It may be noted that during a period following the introduction of Paragraph 175 "until Hitler's accession to power in 1933", movements of opposition to the criminalisation of same-sex acts, among both "homosexual emancipation movement" and socialists remained unrivaled in neighboring european states; a fact partially reflected by the petition of the Reichstag by the formation of what has been termed the first "gay liberation organization" in the form of the Scientific Humanitarian Committee, formed in 1897 . The extent to which we can logically align this organisation to the political trajectory of "gay liberation" is deeply questionable, yet it’s formation does say something about the response the law engendered from a range of Germanic society.
We find an expression of opposition among socialists expressed by many of the leading members of the Social Democratic Party of Germany (SPD) during this period. August Bebel, co-founder and parliamentary leader of the SPD of Germany was the first politician to speak within the Reichstag against the criminal code in 1989, supporting a petition calling for the repeal of the statute. Bebel noted that in a society in which so called 'unnatural fornication' is prevalant among "all sections of society", enforcement would require the Prussian state to "build two new penitentiaries just to handle the number of violations against Paragraph 175 committed within the confines of Berlin alone" .
Sections of the Social Democratic reichstag representatives delegates "distanced themselves firmly" from Bebel, while a commitment to the rights of Homosexuals did not remain an approach articulated within the political programme of the SPD 
However Bernstein would not be an isolated figure in opposition to Paragraph 175, other prominent members of the German Social Democratic Party would oppose the statue and raise issues of relevance to the rights of persecuted sexual minorities. Within one of two articles published in Die Neue Zeit leading SDP theorist Eduard Bernstein elaborated a view upon the trial of Oscar Wilde, prosecuted under the Criminal Law Amendment Act, within the United Kingdom. Bernstein including an acknowledgment that
within the German social-democratic movement, very far-reaching differences of opinion regarding the position society should adopt towards those sexual activities which do not fall within the ambit of what passes for normal 
In understanding how to characterise the 'crime' for which Wilde had been persecuted, Bernstein rejects judgements "based on more or less arbitrary moral concepts" instead noting the historic variability of what are considered 'unnatural acts' in reference to the historic prevalence of same-sex sex acts within Greek and Roman society.
 Leftist Sexual Politics and Homosexuality: A Historical Overview