Judge: Police can create a fake Instagram account sans warrant
The specific case that the judge was ruling on involves one Daniel Gatson, who was charged with stealing over $3 million in jewelry. Gatson posted pictures on his Instagram account that showed the jewelry he allegedly stole. He shared the pictures with an Instagram account of an individual that was in reality, the DEA. The judge's decision denies the defendant's request to prevent his Instagram pictures from being used as evidence during his trial.
It should be noted that the decision by the judge wouldn't have applied in a 2010 case where a DEA official created a false Insagram account using the real name of a female suspect being tracked by the agency. Risque photos of the suspect were taken from her smartphone and used to create the counterfeit account. The difference between the two accounts created by the DEA is that one used a completely false identity, which is allowed by Instagram. The second account used the name of a real person and her pictures without permission, which violates Instagram's Terms of Service.
source: DocumentCloud via ArsTechnica, SlashGear