The major Internet companies sued by Paul Allen for patent infringement will be able to mount aggressive defenses, including arguing that the Microsoft Corp. co-founder sued too late, legal experts said Monday.

News of Mr. Allen's suit, filed Friday in federal court in Seattle against Google Inc., Facebook Inc. and other prominent technology companies is still rippling through Silicon Valley.

The companies have disputed Mr. Allen's claims. They won't comment on their legal strategies.

But in their defense arsenal is the matter of timeliness: Mr. Allen's lab applied for the patents in the late 1990s and they were granted earlier this decade, between 2000 to 2004.

The technologies Mr. Allen cites in the suit are key functions the companies use on their websites. They cover things like pop-up stock quotes and tools that recommend other articles based on what a user is reading.

Some legal experts said the firms could try to convince a court that Mr. Allen waited too long to sue, a tactic that could severely limit any damage award.

The technology has been widely used, and so if it was proprietary, the thinking goes, why would Mr. Allen not have sued years ago?

'If the patentholder just sat on their rights for a long time. . . the patent might become unenforceable,' said Dennis Crouch, a law professor at the University of Missouri. Timeliness is often raised as a defense in patent suits, but is untested in the courts, legal experts said.

David Postman, a spokesman for Mr. Allen, declined to comment and said Mr. Allen and his attorneys weren't available.

The suit seeks unspecified damages and also asks for an injunction to stop the companies from infringing on the patents. Named in the suit are Google, Facebook, eBay Inc,., Apple Inc., Yahoo Inc., AOL Inc., Netflix Inc., Office Depot Inc., OfficeMax Inc., Staples Inc. and Google's YouTube subsidiary.

'It's just unlikely he wants to shut down the Internet,' Mr. Crouch said. 'More likely he wants money out of this and some acknowledgment that his work 20 years ago was on the right path.'

The suit, filed by Mr. Allen's Interval Licensing LLC, lists violations of four patents for technology that appear to be key components of e-commerce and Internet-search companies in general.

The technologies in the suit are so core to the companies that a trial victory for Mr. Allen would be significant. Mr. Allen's lab created the technology and his Interval Licensing owns the patents.

His lawyers could seek an award based on a percentage of the revenue the companies derived from the four patents named in the suit. That figure could easily reach more than $100 million, some lawyers estimate.

'He had incredibleforesight into the future of this technology,' said Alex Poltorak, chief executive of General Patent Corp., which assists plaintiffs in patent suits. 'He certainly deserves a return on his investment.'

Patent cases can take more than a year to wind through the courts; many end up in licensing deals.

Some legal experts said Mr. Allen's lawsuit could be a foray toward obtaining licensing deals, albeit an aggressive one.

Dionne Searcey / Justin Scheck

• patent [´peitənt, ´pæ-] a.专利的 n.专利品 (初中英语单词)
• federal [´fedərəl] a.联邦的，联邦制的 (初中英语单词)
• prominent [´prɔminənt] a.突起的；凸出的 (初中英语单词)
• comment [´kɔment] n.&v.评论；评注；注意 (初中英语单词)
• recommend [,rekə´mend] vt.推荐；使受欢迎 (初中英语单词)
• convince [kən´vins] vt.使确信；使认识错误 (初中英语单词)
• interval [´intəvəl] n.间隙；(工间)休息 (初中英语单词)
• victory [´viktəri] n.胜利，战胜 (初中英语单词)
• percentage [pə´sentidʒ] n.百分数；比例；部分 (初中英语单词)
• executive [ig´zekjutiv] a.行政的 n.行政官 (初中英语单词)
• decade [´dekeid] n.十年(间) (高中英语单词)
• severely [si´viəli] ad.剧烈地；严格地 (高中英语单词)
• holder [´həuldə] n.所有物；土地；股份 (高中英语单词)
• crouch [krautʃ] vi.卷缩；蹲伏 (高中英语单词)
• significant [sig´nifikənt] a.重要的；意义重大的 (高中英语单词)
• revenue [´revinju:] n.税收；收入 (高中英语单词)
• incredible [in´kredəbəl] a.不能相信的；惊人的 (高中英语单词)
• aggressive [ə´gresiv] a.进攻的；侵略的 (英语四级单词)
• injunction [in´dʒʌŋkʃən] n.指令；法院禁令 (英语四级单词)
• foresight [´fɔ:sait] n.先见，深谋远虑 (英语四级单词)
• arsenal [´ɑ:sənəl] n.兵工厂；军械库 (英语六级单词)
• applied [ə´plaid] a.实用的，应用的 (英语六级单词)
• spokesman [´spəuksmən] n.发言人 (英语六级单词)
• unlikely [ʌn´laikli] a.不像的；未必可能的 (英语六级单词)
• acknowledgment [ək´nɔlidʒmənt] n.承认；鸣谢 (英语六级单词)
• albeit [ɔ:l´bi:it] conj.即使；纵使；虽然 (英语六级单词)