SAN FRANCISCO — John Doerr really needed a win, and late Friday the esteemed venture capitalist got one of the biggest of his career: a jury’s complete dismissal of gender discrimination claims against his firm, Kleiner Perkins Caufield & Byers.  But success in the courtroom is a tricky thing, and Kleiner’s victory contains perils that his company will still have to overcome, such as its image as a boys’ club. There is a less obvious one, too, which is how the details that came out during the trial may upend perhaps the most celebrated aspect of venture capitalism: investing on instinct, almost impulsively.  In its glory days, venture capital was a freewheeling enterprise with few rules and scant documentation. That may all be over now.  This probability became apparent during the testimony of Ellen Pao, the former junior partner who was suing Kleiner. She said that she had discovered Twitter as a potential investment for the venture capital firm. But Kleiner disputed that Ms. Pao had found Twitter because she could not prove it. Twitter is now worth $32 billion.  “There is not a single piece of evidence to suggest Ellen Pao ever sourced Twitter,” Kleiner’s lawyer, Lynne C. Hermle, told the jury. “Not one. I can say I sourced Twitter, too, but that doesn’t mean it’s so. There should be evidence — written evidence, consistent with the practices of Kleiner — if that’s true, and there is nothing.”  The issue of having to document an idea is now set to ripple through Silicon Valley. While the truth of what did or did not happen with Twitter was one of the many unresolved points of the trial — Kleiner did invest later in Twitter, but at such a high valuation that it did not qualify as a home run — it is a pretty good bet that the next time a junior partner at Kleiner or any other venture firm thinks he or she has come up with something great, the partner will record it in emails, memos, diaries and possibly stone tablets.  “As a result of hearing the testimony, I would advise my clients to document any information and make notes, and perhaps formal memoranda, regarding their contributions to the firm and their decisions,” said Kathleen M. Lucas of the Lucas Law Firm in San Francisco.  Formalizing so much about the venture capital process goes directly against the go-with-your-instinct approach that has been a cornerstone of the industry. Mr. Doerr rose to fame because his intuition was so good about which entrepreneur to invest in. Not much separated the potential winners from the losers.  “I’m still looking for a bunch of burrito-eating Stanford kids who walk in with no idea what a business plan is, we write them a check and work intensively with them for several months, and — boom! — you’ve got a company with a market cap of $2 billion,” Doerr said in a 1999 book, “The Silicon Boys.” In cartoon form, that summarizes Kleiner’s investment in Google, made at about that time.  Yet now the stakes are too high in venture capital for any approach other than writing it all down, however much it goes against the go-with-your-gut heritage. The testimony in the trial with Ms. Pao repeatedly circled back to the issue of who got credit for profitable investments.  “Kleiner needed a win. Everybody needed a win. I could use some wins,” Mr. Doerr testified about another disputed find of Ms. Pao’s, RPX.  Margaret O’Mara, an associate professor of history at the University of Washington who has studied the history of technology, said the Pao case highlighted how Silicon Valley has been based on a culture of personal connections and personality-driven deals. Those considerations still drive decisions “even though the Valley is no longer this little outlier community of small electronics manufacturers,” she said.  Beyond the impact on venture capital, reaction to the verdict and analysis of what it means for Silicon Valley diversity has been swift.  “There are people that will take this ruling and say there is no problem with gender discrimination, and that would be a horrible shame,” said Sam Altman, president of Y Combinator, who sits on the board of directors of Reddit, where Ms. Pao is now interim chief executive. “I hope it makes men and women listen to people’s experiences in their careers and form their opinions about challenges that any group, and in this case women, face.”  Alexis Ohanian, co-founder and chairman of Reddit, added that he was “glad to see that her actions have helped to push forward the conversation about gender parity not just in the tech sector but in the business world.”  Even without a victory for Ms. Pao, the case succeeded in putting the issue of women in technology in the spotlight. Tracy Young, a founder and chief executive of PlanGrid, a San Francisco start-up that offers apps for construction workers, said Ms. Pao highlighted how “sexual discrimination is a real problem. There is a lot we must do and can do to prevent it.”  “Issues about diversity are more at the forefront than they have ever been,” said Bridget Frey, chief technology officer at the online real estate company Redfin. “Without that dialogue, we can’t help each other get better,” she said.  Brian X. Chen, Nick Wingfield and Mike Isaac contributed reporting.  A version of this news analysis appears in print on March 29, 2015, on page A22 of the New York edition with the headline: After Kleiner Trial, Silicon Valley Enters a More Cautious Era. Order Reprints| Today's Paper|Subscribe
A recurring issue was who originated investment ideas at the venture capital firm and the lack of documentation to support claims.