"HFT-Limiting Experiment Underway in Germany"

In the U.S. we have the  Securities and the Securities Exchange Acts but nobody pays any attention to them.*
From All About Alpha:

Germany’s Bundestag voted Thursday, February 28, approving a bill aimed at limiting the abuses of high-frequency trading.

If you’re a pessimist, you are even now muttering, “we’re from the government, and we’re here to help.”

If you’re an optimist, [and one who lives, invests, and seeks alpha for the most part outside of Germany] you may be happy to have Germany undertake an experiment in this respect. Other countries and their regulators may well observe how this initiative plays out and make more informed decisions themselves as a consequence.

There are also likely to be those who will differ from Germany even within the European Union. Meanwhile, the globe is a big place, and there are lots of laboratories in which the critical questions of exchange structures and infrastructures may yet be tested.

The Problem Defined and Addressed
But let’s look at the news from Germany:  The problem, as the government there saw it, was that firms that traded exclusively on their own accounts (including most HFT traders) didn’t fall under the authority of the Federal Financial Supervisory Authority (BaFin). The new law solves that problem, explicitly letting BaFin supervise high-frequency trading that it otherwise couldn’t have touched.

A document posted by BaFin in November described the pending bill in an English-language outline, here.

Intriguingly, the bill would require exchanges to mandate a minimum tick size and order-to-trade ratio on an instrument-by-instrument basis....MORE

*The U.S. law is pretty straightforward, it says your 'puter can't spoof my 'puter but for whatever reason the SEC has chosen to not enforce it.

15 USC § 78i - Manipulation of security prices
 This subchapter may be cited as the “Securities Act of 1933”.

(a) Transactions relating to purchase or sale of security

It shall be unlawful for any person, directly or indirectly, by the use of the mails or any means or instrumentality of interstate commerce, or of any facility of any national securities exchange, or for any member of a national securities exchange— 

 

(1) For the purpose of creating a false or misleading appearance of active trading in any security other than a government security, or a false or misleading appearance with respect to the market for any such security...

And from the '34 Act:
 
Securities Exchange Act of 1934, Section 9 -- Manipulation of Security Prices

a. Transactions relating to purchase or sale of security

It shall be unlawful for any person, directly or indirectly, by the use of the mails or any means or instrumentality of interstate commerce, or of any facility of any national securities exchange, or for any member of a national securities exchange--

1. For the purpose of creating a false or misleading appearance of active trading in any security registered on a national securities exchange, or a false or misleading appearance with respect to the market for any such security, (A) to effect any transaction in such security which involves no change in the beneficial ownership thereof, or (B) to enter an order or orders for the purchase of such security with the knowledge that an order or orders of substantially the same size, at substantially the same time, and at substantially the same price, for the sale of any such security, has been or will be entered by or for the same or different parties, or (C) to enter any order or orders for the sale of any such security with the knowledge that an order or orders of substantially the same size, at substantially the same time, and at substantially the same price, for the purchase of such security, has been or will be entered by or for the same or different parties.
   
   
2. To effect, alone or with one or more other persons, a series of transactions in any security registered on a national securities exchange or in connection with any security-based swap agreement (as defined in section 206B of the Gramm-Leach-Bliley Act) with respect to such security creating actual or apparent active trading in such security, or raising or depressing the price of such security, for the purpose of inducing the purchase or sale of such security by others.