Bostwick produced 103 witnesses， many of them young Triangle employees dressed in their Sunday best. Through his witnesses Bostwick tried to establish that the fire quickly cut off escape through the Greene Street door， causing the panicked workers to turn to the Washington Place door——a door the prosecution contended was locked. More than a dozen prosecution witnesses testified that they tried the door and were unable to open it. Katie Weiner told jurors， "I pushed it toward myself and I couldn't open it and then I pushed it outward and it wouldn't go. I was crying， 'Girls， help me！' Other witnesses testified that Blanck and Harris kept the door locked to prevent employees from pilfering shirtwaists. （On the stand， Harris admitted to an almost obsessive concern with employee theft even though he conceded that the total value of goods taken over the years was under $25）。

　　Bostwick used the testimony of Kate Gartman and Kate Alterman to prove that the locked door caused the death of Margaret Schwartz. Both had emerged with Schwartz from a ninth-floor dressing room to find the floor in flames. Alterman offered compelling testimony of concerning Schwartz's death：

　　I wanted to go up Greene street side， but the whole door was in flames， so I went in hid myself in the toilet rooms and bent my face over the sink， and then ran to the Washington side elevator， but there was， a. big crowd and I couldn't pass through there. I noticed some one， a whole crowd around the door， and I saw the Bernstein， the manager's brother trying to open the door， and there was Margaret near him. Bernstein tried the door， he couldn't open it and then Margaret began to open the door. I take her on one side I pushed her on the side and I said， "Wait， I will open that door." I tried， pulled the handle in and out， all ways——and I couldn't open it. She pushed me on the other side， got hold of the handle and then she tried. And then I saw her bending down on her knees， and her hair was loose， and the trail of her dress was a little far from her， and then a big smoke came and I couldn't see. I just know it was Margaret， and I said， "Margaret，" and she didn't reply. I left Margaret， I turned my head on the side， and I noticed the trail of her dress and the ends of her hair begin to burn.

　　In his cross-examination of Alterman， Max Steuer settled on an unusual approach. He asked Alterman to repeat he account of Margaret Schwartz's death again and again. Each time， the words Alterman used were very similar， but not identical. Steuer hoped that the repetition of phrases （e.g.， "curtain of fire，" a desperate man running around "like a wildcat"） would suggest to the jury that the witness had been coached by the defense. In redirect， Bostwick asked his witness why she used similar language each time she was asked to describe Schwartz's death. Alterman replied， "Because he asked me the very same story over and over， and I tried to tell him the same thing， because he asked me the same thing over and over." Yet， to many observers， Steuer had succeeded in damaging Alterman's credibility without ever directly attacking it.

　　The defense presented witnesses designed to show that the ninth floor deaths resulted from fire blocking the Washington Place stairwell， even though the door was actually open. Various salesmen， shipping clerks， watchmen， painters， and other building engineers told of their passage through the disputed ninth floor door——though， of course， none had attempted to exit through the door at the time of the fire. Louis Brown said a key was "all the time in the lock." Ida Mittleman said a key was attached to the door by tape "or something." Defense witness May Levantini testified that a key to the lock hung from a piece of string. Levantini was the prosecution's key witness， telling jurors that she turned the key in the door and opened it only to find "flames and smoke" that made her "turn in and run to the elevators."

　　Bostwick contended Levantini "lied on the stand." He said numerous witnesses described going down the stairwell that Levantini said she saw in flames， and all that went down made it out untouched.

　　After presenting 52 witnesses， the defense rested.

　　On December 27， Judge Crain read to the jury the text of Article 6， Section 80， of New York's Labor Law： "All doors leading in or to any such factory shall be so constructed as to open outwardly where practicable， and shall not be locked， bolted， or fastened during working hours." Crain told the jury that in order to return a verdict of guilty they must first find that door was locked during the fire——and that the defendants knew or should have known it was locked. The judge also told the jury that they must find beyond a reasonable doubt that the locked door caused the death of Margaret Schwartz.

　　After deliberating for just under two hours， the jury returned a verdict of not guilty. After the verdict， one juror， Victor Steinman declared， "I believed that the door was locked at the time of the fire， but we couldn't find them guilty unless we believed they knew the door was locked."

　　Surrounded by five policemen， Blanck and Harris hurried through the judge's private exit to Leonard Street. Those in the crowd that saw the men yelled， "Justice！ where is justice！" The defendants ran to the nearest subway station， the crowd in pursuit.

　　In March 1912， Bostwick attempted to prosecute Blanck and Harris again， this time for the manslaughter death of another fire victim， Jake Kline. However， Judge Samuel Seabury instructed the jury that the men were being "tried for the same offense， and under our Constitution and laws， this cannot be done." He told the jury to "find a verdict for the defendants."

　　Three years after the fire， on March 11， 1914， twenty-three individual civil suits against the owner of the Asch Building were settled. The average recovery was $75 per life lost.

　　The public outrage over the horrific loss of life at the Triangle Shirtwaist Factory led to the creation of a nine-member Factory Investigating Commission. The Commission undertook a thorough examination of safety and working conditions in New York factories. The Commission's recommendations led to what is called "the golden era in remedial factory legislation." During the period 1911 to 1914， thirty-six new laws reforming the state labor code were enacted. One member of the Commission was Frances Perkins， who later would become Secretary of Labor in the Roosevelt Administration. Recalling the impact of the Triangle Shirtwaist Fire years later， Perkins said：

　　Out of that terrible episode came a self-examination of stricken conscience in which the people of this state saw for the first time the individual worth and value of each of those 146 people who fell or were burned in that great fire……We all felt that we had been wrong， that something was wrong with that building which we had accepted or the tragedy never would have happened. Moved by this sense of stricken guilt， we banded ourselves together to find a way by law to prevent this kind of disaster……It was the beginning of a new and important drive to bring the humanities to the life of the brothers and sisters we all had in the working groups of these United States.