English law delivered its verdict at Southwark Crown Court where five members of the DPM graffiti crew were jailed – one, Andrew Gillman, for two years... By contrast, just down the road, the riverside facade of Tate Modern had been covered in giant murals by six urban artists with international reputations, including Blu from Bologna, Faile from New York, and Sixeart from Barcelona, in the first display of street art at a major museum" The courtroom and the museum were so close that artists supporting the artists on trial worked on their art at the Tate during one lunchtime adjournment. "There is a huge irony in the juxtaposition of the two events," said one of the artists.
The urban cityscape "offers the colorful, provocative, illegal "eyesore" that is graffiti. Although many consider the spray-painted pieces a nuisance, graffiti has been gaining recognition from the art world more and more as a legitimate form of art... Most people think of graffiti, they imagine "tags," or a stylized writing of a person's name... probably the most popular form, graffiti art is much more than that. It can mean a colorful mural with a message of diversity or a black and white stencil piece protesting police brutality. In each case, graffiti art makes a statement.... The manner in which graffiti art is executed is the only obstacle it faces in being considered an art form.... Although its artistic merits can't be denied, graffiti is still in fact a form of vandalism. Artists tag both public and private property, which becomes costly for tax payers and business and property owners."
There is great interest in making the determination and lots of opinion on every side of the discussion... here and here and here