For both The sweeping rules of censorship changed the entire industry, ushering in the silly Silver Age while also all but destroying the horror and crime genres of comics altogether. Though the CCA eventually fell out of favor before being almost entirely disregarded in the 90s and beyond, it was ultimately hoisted by its own petard, a victim of short-sightedness on the part of its creators.
In 1954, psychiatrist Fredric Wertham's book Seduction of the Innocent was gaining traction among American readers - and lawmakers (who no doubt saw a way to increase their standing among easily-influenced voters). The book was, in many ways, fundamentally flawed (Wertham claimed Wonder Woman's super-strength made her a lesbian, which was seen as a mental disorder at the time), but his book nevertheless struck a chord with the general public. Thus, after a public outcry and a subsequent formation of the United States Senate Subcommittee on Juvenile Delinquency, the Comics Code Authority was established, and changes were immediate.
Among the many rules enforced by the CCA, excessive violence - either on- or implied - was banned, along with the words "horror" or "crime" in the titles. Monsters such as zombies, werewolves, and other grotesques were forbidden. Portrayal of all drugs was banned, along with any negative portrayal of law enforcement officers or government officials. In addition, "...in every instance good shall triumph over evil and the criminal punished for his misdeeds." This essentially killed books like 1975's Joker solo title; the Joker simply wasn't as interesting if he was arrested by the police at the end of every issue.
But the CCA's regulations didn't only restrict storytelling - they got in the way of the very morals the CCA wanted to promote. With heavy restrictions on violence or even the depiction of crime, criminals were essentially toothless, and readers realized their comeuppance was a foregone conclusion in every issue. Put that together with the rule stipulating that law enforcement officers must always be portrayed in a positive light; the American justice system was clearly meant to be seen as infallible - which, thanks to the civil unrest, corrupt cops, and police brutality of the 60s, was most certainly not.
The infamous Spider-Man story portraying drug abuse in a negative light certainly damaged the CCA, but it ultimately fell due to its own practices. Superheroes were created to fight supreme evil such as Adolf Hitler; if the CCA existed during World War II, he would've been captured in Issue #1...thus negating the terrible threat he posed to the world. The CCA's demise was ultimately a positive development for both Marvel and DC Comics, and the companies' stories have developed as a result.
