It's an interesting time in the House of Lords at the moment. The Coalition Government is continuing to push through controversial legislation - despite all party concerns in the House of Lords. It has suffered a number of significant defeats.
However the Executive retains some high powered weapons to force its will. In the Commons it can push legislation through the House with limited scrutiny. Ministers are bound by the doctrine of collective responsibility - which means that they are expected to vote with the Government (whatever their own personal reservations) or RESIGN. Commons whips can make persuasive arguments to backbenchers who are desirous of re-selection or advancement. The convention that a government defeat on a motion of confidence will bring down a government is also a useful threat to use against backbenchers who are minded to rebel. (John Major famously reversed a defeat on the Maastricht Bill in 1993 by bringing back the issue the next day as a motion of confidence - see the Wikipedia article). Rebels in marginal seats decided they preferred to fight another day than face a General Election at which they faced almost certain defeat.
Recently, and very controversially, they refused to accept Lords Amendments by using a wider definition of "Money Bill" than had been used previously (read the row that ensued in the House of Lords (Hansard) - I was there to watch this from the gallery).
Sadly, the most important battles against the Welfare Reform Bill; the Legal Aid, Sentencing and Punishment of Offenders Bill (LASPO) and the Health and Social Care Bill has been fought in the Lords, rather than in the Commons. This is for the reasons set out in the second paragraph of this post.
Opposition Peers (Labour); and Crossbenchers have been at the forefront of these fight. Some limited support has come from dissident Lib-Dem Peers - but most of the time they have backed the Government. Breakdown of votes by party can be found on the Lords Divisions database.
Labour Peers have been buttressed by tweets supporting their campaign - and have used tweets to get out the message. This week they established a website - Labour Lords. Whether you agree with them or not (and in the interest of full disclosure I have worked for - on both a paid and unpaid basis - some of those Peers, and continue to work with them) - it is worth following - just to see how - in this technological age - opposition in the House of Lords is carried out.