Last month, the Georgetown Law School brought together financial and legal professionals, regulators and academics to commemorate the 40th anniversary of the Williams Act, at an event called “The History and Future of U.S. and Global Takeover Regulation: The Williams Act 40 Years On.”

The Williams Act was passed in 1968 to regulate tender offers. At the time, the corporate bogeyman du jour was the “Saturday Night Special,” in which a bidder would embark on a pre-offer buying raid to establish a substantial beachhead of ownership at a reduced price. This spree would be followed by a few-days-long, first-come, first-served public tender offer.

Shareholders would then stampede to tender into this offer, fearing what the corporate raider would do to the company and that the price of their shares would drop. The Williams Act was passed at the behest of the Securities and Exchange Commission to regulate these practices.

Georgetown’s conference was great — a model for bringing together all of the community to discuss regulatory issues in a comprehensive and deliberate matter.

I spoke on a panel called “The State of the Global Mergers & Acquisitions (M&A) Marketplace.” The other participants on my panel were Robert Kindler, a vice chairman at Morgan Stanley; Dennis Berman of The Wall Street Journal; and James C. Morphy of Sullivan & Cromwell. (Mr. Morphy is representing Microsoft in its bid for Yahoo.) It was a wide-ranging look at the M&A markets, covering topics including sovereign wealth funds, shareholder activism and the use of derivatives by those shareholder activists.

My pitch on the panel was for the S.E.C. to take this 40th anniversary as an opportunity to reexamine its takeover regulation. And to do what it hasn’t done since 1983: Appoint a panel of experts to rethink takeover law. (Marty Lipton, the prominent takeover lawyer at Wachtell, Lipton Rosen & Katz, was on that 1983 panel, so the S.E.C. could even have some continuity.)

Here’s why they should do it. The world was different back in 1968, when the Williams Act was passed. We are operating with a federal takeover code that was enacted for a different time and circumstance — an age when the tender offer was new, poison pills and other takeover defenses nonexistent, and other federal takeover regulation, such as antitrust and national security reviews and waiting periods, virtually absent. This world is lost to time.

In the 1960’s, an offerer could simply launch a tender offer, and a company was relatively defenseless. But the poison pill has changed all that and shifted the way hostile takeovers are accomplished.

Now, a proxy contest is required in any serious battle for corporate control (e.g. Microsoft and Yahoo). The result is that, according to FactSet MergerMetrics, there were only 8 hostile tender offers last year, compared with 60 friendly ones. And M&A numbers via merger and proxy are at least triple these. The regulation of the Williams Act is regulating to a pittance of takeovers and M&A transactions generally.

Moreover, the S.E.C. has largely receded from making takeover jurisprudence — this has now gone to the small but very active state of Delaware.

Professor Sam Thompson of Penn State Law School discussed these problems at the conference. Mr. Thompson said he would overthrow Delaware, but in my view — a view that has changed over the years — Delaware largely does a good job of regulating takeovers. The S.E.C.’s rules still need to be revised to interact with them and vice versa.

In any event, the takeover scene has changed substantially from 1968, let alone 1983, the time of the last full review.

For example, Delaware requires that a shareholder meeting be held within 13 months of the last annual meeting. But if you are a company in the midst of an accounting restatement, you cannot file your proxy with the S.E.C. for that meeting. You’re stuck. In a takeover contest, this can permit you to delay holding your annual meeting, something that benefited BEA Systems when it was in the middle of an options backdating investigation.

More tellingly, though, the tender offer rules may not be up to date and otherwise inapplicable. Take Rule 14e-5.

Rule 14e-5 was promulgated in 1969 as Rule 10b-13 to prohibit bidder purchases outside of a tender offer from the time of announcement until completion.

The primary reason put forth by the S.E.C. for barring these purchases in 1969 was that they “operate [...] to the disadvantage of the security holders who have already deposited their securities and who are unable to withdraw them in order to obtain the advantage of possible resulting higher market prices.”

This is no longer correct; bidders are now obligated to offer unlimited withdrawal rights throughout the offer period. Moreover, Rule 10b-13 was issued at a time when targets had no ability to defend against these bidder purchases. They were yet another coercive and abusive tactic whereby the bidder could obtain control through purchases without the tender offer, thereby exerting pressure on stockholders to tender before the bidder terminated or completed its offer on the basis of these purchases.

This is not feasible today. Poison pills and second- and later-generation state takeover statutes act to restrict these purchases to threshold noncontrolling levels without target approval. With these developments, the original reasons underlying the promulgation of Rule 10b-13 no longer exist.

Furthermore, Rule 14e-5 has never applied to bar purchases while a merger transaction is pending. One reason the JPMorgan Chase transaction with Bear Stearns was structured as a merger was to side-step this rule and permit JP Morgan’s market purchases.

Presumably, this path dependency was set in 1969 because a bidder in a merger situation requires target agreement; the target can therefore contractually respond to and regulate this conduct. But whatever the reason, today, a bidder who runs a proxy contest without a tender offer is permitted postannouncement purchases during the contest.

Unsolicited bidders will therefore initially characterize their offers as mergers in order to leave the option of such purchases open. The result is preferential bias towards mergers over tender offers, discrimination that no longer seems to make sense in a world where a takeover transaction will not succeed unless the original or replaced target board agrees to it. Any prohibition on outside purchases should apply to both merger and tender offer structures — or to neither.

And I could go on. There are numerous other examples. Fairness opinion disclosure has become a mess, with the Delaware courts now actively regulating this issue in a different way than the S.E.C. It is time for some harmony here.

The continued rationale for the prohibition on short and hedged tendering in partial offers is questionable in light of today’s deeply liquid capital markets. S.E.C. disclosure standards are arguably not copious enough or require disclosure that is no longer appropriate or applicable to the present paradigm.

Meanwhile, wholesale repeal of the all-holders/best price rule may be appropriate in today’s takeover environment in order to permit transaction participants to order their own economic rights. Alternatively, the all-holders/best price rule may be better extended to fully encompass the pre- and post-tender offer periods. Finally, withdrawal rights are arguably unnecessary in a world where their coercive aspect can be regulated by targets and where irrevocable tenders can provide bidders flagship support in unsolicited transactions.

Finally, given that all of the takeover action today revolves around the proxy contest, it is time to yet again consider the regulatory distinctions between mergers and tender offers.

The most glaring example of this unwarranted discrimination is the undue timing advantage tender offers have over mergers. Tender offers currently have a minimum offer period of 20 business days; this compares with a two- to three-month minimum period to complete a merger. Again, the justifications for this distinction appear no longer relevant in a world where target consent is necessary, as the target can negotiate its preferred takeover structure. One way to address this disconnect is to lengthen the tender offer period; perhaps an optimal result for the reasons discussed above.

The other salve is obviously to shorten the merger period to bring it in line with the period for tender offers. This would require the S.E.C. to revise Rule 14a-6 of the Exchange Act and reconsider its preclearance procedures for proxy statements before mailing and solicitation of proxies. Depending upon the scope of revision it would also require the S.E.C. to compel the stock exchanges to revise their own proxy solicitation regulation and preempt conflicting state laws. Ultimately, whatever the direction of the cure, the point is that the original timing distinction under federal law for these two structures no longer exist and appear inappropriate.

There are other cases where this discrimination no longer appears sustainable in light of a target’s effective ability to control takeover structure. The federal disclosure requirements in mergers and tender offers are distinct, with variant and increased or lesser disclosure required for each. The propriety of this differentiation, on the whole, no longer seems apposite: full harmonization should be considered. Moreover, the all-holders/best price rule is applicable only to tender offers. There is no longer a reason for this. If the rule is maintained, application of the rule to merger transactions (or elimination in the case of tender offers) may be appropriate in order to stem the systematic bias that the rule, as currently interpreted, provides towards merger transaction. There is also the matter of bias under Rule 14e-5 discussed above.

The S.E.C. has attempted to address some of these issues piecemeal, such as attempting to put stock and cash tender offers on parity. (For those who are watching, there actually was a stock exchange offer announced this past week: Smith Internationals agreement to buy W-H Energy Services in $3.2 billion deal.) The S.E.C. has also recently put forth some solid proposals to reform the cross-border rules.

But, as highlighted by the suggestions above, the time has come for a global rethink of the S.E.C.’s takeover regulation.